On branching, from an SVN tutorial – http://svnbook.red-bean.com/en/1.1/ch04.html#svn-ch-4-sect-1
A solid, easy to follow Git tutorial – http://www.kernel.org/pub/software/scm/git/docs/gittutorial.html
Another Git tutorial, same basic ideas – http://www.sourcemage.org/Git_Guide