Start with the basic strumming patterns and finger picking patterns and gradually move the difficult up a bit each week or every time you feel comfortable with your skills.
Here's a great lesson from Pebber, it's really good and you'll get a good knowledge on strumming patterns and some of the history behind it: search on YouTube Strumming Concepts part 1 (couldn't post the link).
If you like Jazz/big bands, that's a treat. I love this video.
If you need anything else, keep us posted.
Ah, and one more thing, if you can, try to practice with a metronome, it's really important to develop good timing - it's essencial to become a good rhythm guitar player (and to become a good musician, to be honest).
See ya, man.