I taught myself how to play guitar. Luckily I had others around to ask questions. I would suggest picking up a book that shows you the fingerings for the various chords. I have one at home but I can't think of the title, I'll try to post it later.
As for music to start playing, I would suggest that you look at your piano music. You might have guitar chords specified above the staff. Also if there is a particular song that you are looking for, do a search and see if you can find a TAB for that song online... websites that I have used for TABs are
Fretplay and
Tablist . Fretplay also has a "how to read TABs" section...
Hope that helps...