I agree with fayyaz that there is a lot of background material that is
needed by someone in computer science who would like to get into
computational biology. Once you get the background, then you can best
learn about protein folding through scientific journals such as the
Journal of Computational Chemistry. However, to get started, I would
reccommend an introductory book on molecular modeling such as
"Molecular Modeling and Simulation", by T. Schlick. It has a good
introduction to molecular mechanics and molecular dynamics, but it
doesn't cover ab initio methods. However, the simpler molecular
mechanics approach might be a better way for you to get started because
it could give you a more intuitive feel for what is going on with
molecules. Starting off with the more rigourous QM methods might be
biting off more than you can swallow. Buying an introductory book may
cost you some money up front, but it can save you a lot of time by
giving some clear explanations of the basic concepts, which is
sometimes harder to find from just reading journal articles.