The last few years have seen some fantastic public repository sites come to the fore, and sharing source code is easier than ever. While I personally prefer
git and
github, many developers find
SVN and
google code are a little more approachable. Windows users especially gravitate toward
Tortoise. The point of these tools and sites, if it's not clear, is to upload and share the source code for your projects with the rest of the world. A lot of people learn best by example, and having a functional application out there to examine and pick apart is a phenomenal, invaluable community resource.