This page explains normal usage of Subversion. Before being able to run the commands here, you must install and configure Subversion, and do the initial checkout of TeX Live. After that, normal usage goes as follows ($ represents the prompt).
$ cd /your/checkout $ svn update U foo.tex [normal - got new version from repository]
$ cd /your/checkout [create new files and/or directories] $ svn add newfile1 newfile2 newdir
$ cd /your/checkout $ svn update U foo.tex [normal - got new version from repository]
$ cd /your/checkout $ svn status # "status" lists files modified/added M bar.tex [normal - modified by you, not yet checked in] A baz.tex [normal - new file you've added, not checked in] [... and/or ...] $ svn diff # "diff" shows actual differences in contents
$ cd /your/checkout $ svn commit -m"log message describing changes"
As you might guess, the above is just a primer for getting started with Subversion. The Subversion web site and users mailing list have much more. Also, the complete Subversion reference manual is available online (or you can buy a printed copy, if you like to read on paper). The GCC Svn Wiki may be helpful.
One extra note: you can check out the tree as of a certain date with a command like this:
$ svn update --revision {2006-08-01}(You can also give precise times, or use revision numbers rather than dates, etc. The Subversion documentation explains in detail.)
A brief explanation of how TeX Live and its components are built and staged is available separately.
P.S. Subversion creates a .svn subdirectory at the top level of your checkout. Don't delete .svn or touch anything in it - nothing will work if it is tampered with.