How can I learn about proofs for computer science?

Proofs are proofs. The basic logical structures are independent of the mathematical subject area, so there’s no real loss in starting with a general introduction to the subject. You’ll find a list of books on the subject here; it includes the book by Daniel Solow that Gerry Myerson mentioned. It also includes How to Prove It: A Structured Approach, by Daniel J. Velleman, which I think is a significantly better book. (It’s also cheaper and gets some very good reviews at Amazon.) I taught from the first edition of Transition to Advanced Mathematics, by Richard St. Andre, D. Smith, and M. Eggen a good many years ago; if I remember correctly, it was perfectly usable but not so good as the Velleman. I’m not familiar with the others listed.

The discussion and links here are also useful. In particular, the first edition of Bridge to Abstract Mathematics: Mathematical Proof and Structures, by Ronald P. Morash, is available for free download; I also taught from it a number of years ago and remember it as being quite decent.

Finally, some introductory discrete math texts devote significant space to introducing students to reading and writing proofs (and also contain mathematics that students in computer science ought to know). One such is Edward Scheinerman, Mathematics: A Discrete Introduction, which I recommend highly. Another is Susanna S. Epp, Discrete Mathematics with Applications.

There are some books about it. How to Read and Do Proofs, by Solow, for example.