Are you familiar with the concepts and benefits of a version control system?
The previous poster asks all the right questions.
The true benefits don't happen until you start working with others (then its ESSENTIAL), but even by yourself its a useful way of having 'good hygene' when working with text based files (web pages, code etc).
It's worth knowing about and investigating, but only you may know if you want to bother with it.
If you are going to use SVN, use tortoiseSVN (standalone windows SVN client) or eclipses' SubEclipse plugin.