My computer runs Debian and has on it the tools I need. But I have seen the name Fedora often over the years and curiosity made me download it. Fedora ran very slowly from a live CD. To see what it is really like, I tried to put it on the hard drive by the side of Debian. I re-sized /home and made a new partition of the space freed.

When it came to installing Fedora, I followed the instructions at
https://www.maketecheasier.com/dual-boot-ubuntu-fedora/
They are clear enough, but they do not speak of the version I have, in which things are somewhat different.

I am hoping that I shall get advice here about Fedora 27.

you ought to specify where did you stuck, what is your problem exactly? From the other hand you may try to install it in a VM (probably).

I have never worked with a VM and do not want to learn. I want instructions like the ones in the link I gave -- but for the version of Fedora which I have.

I think this would be exactly the same for another fedora or for any other distro. Just replace the version number (if you wish).
Or, if you think it is "somewhat different" please point out those differences.

To make myself clear, I could not follow the instructions at www.maketecheasier because the partitioning menus in them were not what they are in the Fedora I have.

What is "this" in "I think this would be exactly the same..."? Where and with what do I "replace the version number"?

so you have made a new partition for Fedora. If that partition was already created (as you stated in your original post) you only need to run installer using that partition.

I left Fedora to be run from a live DVD and installed Linux Mint to dual boot with Debian.