Yancek, I have come to know how to delete and resize my LVM. Just wanna get your guidance on below points:

1) For deleting LVM, I need to enter my Fedora and execute command. So, if delete sda6, then there shouldn't be any problem in rebooting. Becz after deletion I have to reboot my system. Now the system prompts like this when I boot:

a) It asks for on amonng the 2 options:
Fedora
Other
(by default Fedora is selected)

b) If I select other, then it promts me for one among the below 2 options:
Windows
Unetbootin

c) Now for instialling ubuntu I select Unetbootin. Then I proceed ahead with the installation.
So deleting sda5 shouldn't hinder me reaching this point. Please confirm me this.

2) Now suppose rather than deleting I reduce the size of LVM, then while installation I w'd follow the same steps you told for installing in the new free space. Now there w'd be 3 OS: windows, Fedora and ubuntu. So, may I expect while booting I w'd get the freedom of entering any of the 3 OS.

Hey guys can anyone please solve my issue.
In nutshell I would like to know the following:

See I am installing ubuntu 12.10 via unetbotin (from hard disk, frugal install). When I reboot, I select unetbootin. Then while installation, it says "your installation medium is /dev/sda2". then it comes the window heading "installation type". Now from here i am not able to proceed ahead. I deleted my linux partitions which earlier existed. Though I created 2 partition here with root and swap. But not able to proceed ahead. I am getting error.. I took screen shots of this error and copied from ubuntu to windows partition. Here In windows i am not able to open or do anything with those.The same error message I have typed in my some previous post. Please look at that if reqd.
I am not explaining here more as all details are there in my previous posts except that I have deleted the Linux partitions.
How to move ahead please?

That is referring to where your Ubuntu iso file is that you are installing FROM! Generally, this would be the CD/DVD/Flash drive but since you have the iso on your hard drive (sda2?) you get that message.

How many options do you see? In your case there should be at least three and the one you should select is 'Something Else'. Can you not click the radio button? Also, you say you that you deleted your Linux partitions (does this mean the previous Fedora partitions?) and later you say you created 2 partitions with root and swap. Do you have partitions on which to install Ubuntu or just the windows partitions?

(Yancek thanks for coming back and replying.)
I understand what you mean by this when you say 'something else'. This I understood becz I saw yesterday a youtube video demonstrating ubuntu installation. See the screenshot attached. Yencek these 3 options had I got then there would have been no problem. I had been telling you in my earlier posts that I am not getting any option to select where to install. Had I got these 3 options I would have selected to install alongside windows or 'something else'.

In my earlier post I typed a table showing different partitions. The heading of that window is "Installation type". While installing it asks me for language, i go by default (english), then it shows a window mentioning ,I think,3 options like 'put your computer on electric charge', internet connection to be done.... (something like this). then I click and it shows a window for a few moments saying "your installation medium is /dev/sda2. YOu may not be able to resize, increase, decreasee the partition but you can ...........". I can't do anything here. Then it goes to a window heading "installation type" and what is under is the table I showed you with different partitions. From here I can't proceed ahead.

I deleted those partitions successfully from windows disk management. Please see screen shot. I created partitions on the free space (or unallocated space which I got by deleting partitions in free space. i.e. right click on the free space in windows disk management) directly while installing and also tried by gparted application. But nothing worked. When here I click 'continu" I get error that "an internal error has occured.....".

The catch point w'd be that I am getting this message:- "your installation medium is /dev/sda2.............". i am not getting those 3 options which you wrote.

Yes I deleted my Linux, ie. my previous Fedora partitons. Later I created the 2 partitions and tried and when didn't work I deleted that and now you can see the screenshot to see how it looks like now. I have partitions to install ubuntu as you can see the screen shot. On that 18.55 GB i w'd install ubuntu. On the window heading 'installation type ' which I am getting, there I can see this space. On this space I created partitions (root and swap) but didn't work. Then I tried by keeping it free space and click continue expecting ubuntu w'd make partitions on its own. But here one more catch point: See on this window 'installation type', what ever I do the top row having '/dev/sda' is getting highlighted/selected. So ubuntu may be trying to install on this.

In a nutshell , I say only 1 thing. I don't get the 3 options that is expected to get. That means, it's not accepting the space for installation that I want to give.

While creating bootable iso via frugal install(unetbootin), the hard drive it selected was C: drive. Do you mean this drive it is taking as sda2.
Also I tried by one more means. Here I wanted to change my drive for frugal install from C: to the drive which is free. Please see screen shot "new". this is G drive. But unetbootn only accepts C drive and no other.

Attached Thumbnails

     

That message is not a problem. It is simply informing you that you will not bee able to change that partition (sda2) since your Ubuntu iso file is on that partition. Since that is your windows system, you obviously would NOT want to do that as it would destroy your windows partition. That is an informational message and there is nothing for you to do.

In the image you posted with the Ubuntu screen (the center image) it shows three options. What happens when you click the radio button to the left of Something Else? You should get a new window named Allocate Drive Space and it should show your partitions and free or unallocated space. If you don't see the Allocate Drive Space window, it's not going to work. If you do see it, click on the unallocated or free space in the main window to highlight it then click on the Add tab just below the main window. You should get a new window which shows options such as partition size, Use as (filesystem type: ext4), and a box to check to Format and finally at the bottom, Mount point. Here click the down arrow to the far right and select the option: /, that's for the root of the filesystem and click Continue.

Make sure you only click on free or unallocated space and not accidentally on another partition. As I said above, if you are not getting the Allocate Drive Space window after selecting Something Else as an option, it won't work. I've never tried to use unetbootin to install from an iso on a hard drive and don't know if it will work.

Hey Yancek, this s what i had been telling you that I am not gettiing the ubuntu screen (the middle one). The screenshot (middle one) is the one I took it from the youtube video. PLEASE MAKE IT CLEAR THAT THE SCREEN (WHERE I GET THE 3 OPTIONS) T I AM NOT GETTING. My previous post clearly states this.
what to do when that screen isn't coming. I am getting the message "your installation mediaum is /dev/sda2....." and then I am directly getting the table which I sent you earlier from where I am not able to move ahead. From here I am getting error message that I have already told you

If you don't get any options then I don't suppose there is anything you can do. The unetbootin software can be used in windows to create a Live CD on a flash drive or a usb drive. That is its intended purpose. If you have the Ubuntu from iso on your windows partition, that may be the problem. As I indicated previously, I've never tried to install a Linux iso of any distribution from a windows partition and don't know if it will work. It would be pretty easy to do if you had a Linux distribution with Grub2 bootloader installed to install Ubuntu or one of its derivatives. If you are not getting any of the three options, the iso download may be bad or the unetbootin setup is bad or it won't work from a windows partition.