If you've been playing the drums for 6 years, you should know some guitarists, right? =) Ask some of them to sit down and teach you some stuff.
Simple songs like "For whom the bell tolls" are pretty good to start out with. By just knowing a simple power-chord, how to do muted strumming and a bit of practice, you can start playing rhythm guitar on a lot of songs. Don't bother with solos in the beginning, but never be afraid to experiment and push yourself.
For soloing, you need build a feeling for the guitar and have a good understanding of scales. Musical theory does help a lot. A good thing to practice once you know the most common scales, is to just sit around and play simple melodies. I play melodies I hear on the radio, in computer games, etc. Sometimes when I hear something and think "hey, that would be fun to play on the guitar", I grab the axe and start figuring it out.