When I type in svn commit file.h, I get a screen which has:
--This line and those below will be ignored--
A file.h
And a list of ^G, ^O, etc. below. I would like to know how to go ahead and commit the file into the repository.
That screen allows you to enter a commit message. Describe what's changed in file.h, and then save and exit your editor (it sounds like you're using nano as your editor, in which case you'd hit Ctrl-X). Once you enter a commit message and save it, your changes will be committed to the repository.