Well, wait a minute. If you know the melodies, figuring out the chords for yourself can be some of the best part of having the songs at all. There have been lots of threads about chord theory around here-- maybe someone can point them out for you. But you CAN do your own arrangements and often they are quite simple. This really makes the songs your own. Also, if you play with others who are learning, you can work with each other to do arrangements on stuff the group is interested in.Try this with a song you are interested in now-- go grab your guitar (or whatever you are playing) and and play detective, and see what the chords might be!
~Susan