In this short article i'll summerize how to use SVN in order to work on a project (as the 42sh ? 
). I'll use for example the KoS repository.
First, you have to check-out a repository like :
$>svn co http://sd-10755.dedibox.fr/svn/kos/
co mean check out, so you'll get working source files.
Then, you can work on you project and edit some files. Make many mistakes and fix them. When your project seem to work, and you think it's a good idee to save your work, you can commit it :
$>svn ci -m "Message"
A short explanation : ci = commit, it mean you are sending some files, and "Message" is the comment.
In order to add an existing file : $>svn add file.c and to remove : $>svn rm file.c.
You can copy to : $>svn cp src.c dst.c
So, enjoy it!