I use RH 7.2, I have created a folder “Main” and th “Main” folder has 8 sub folders, The “main” folder and the sub folders are accessed by 4 persons (eg A B C D ). A group has also been created as (tech) and all the 4 members are added to this group. These users have been given access through samba. User (A) creates a word /excel file, then users B,C,D try to access the same file, They get it READ ONLY, it is vice versa for all the other users in the group..

I want all the 4 persons to have read and write access to the files and folders.

chmod the folder to 640

Ha I have given chmod 770, But when a user logins and updates any file from that folder it is still not able to locate that user also belongs to the same group.

how do i set it world.?????

you want to set file permissions to world? or change the group to world?

Both of them are not a good idea but still

chgrp world
chmod 774

the first line will change the owner group to world and the second line will allow world to read but not write or execute

I think this has more to do with the Samba then the folder permissions. Make sure that your Samba shares have "read only=no" set.