get your hands dirty rightaway! There are a lot of FOSS projects which are always looking for new contributors. If you wanna start off with C, make it a point to get familiar with gcc too. I myself have never worked on VB or for that matter much of GUI programming on Windows but I guess you could do something about the Windows ports of various FOSS projects. If you are already familiar with C or C++, you could try your hand at python too. Python provides a high level of abstraction that would help you to write code that is more organized and more focussed on the solution of the problem on hand rather than how to go about solving it.

It would be a good idea to improve your programming skills with problems from Project Euler or various other online coding resources. It won't exactly help you write a piece of software but would make you a good programmer nonetheless.

All the best!