http://en.wikipedia.org/wiki/SHA-2#Examples_of_SHA-2_variants has a pretty good psuedo code of the SHA-2 algorithm.
The diagram above is used to represent a single round of the SHA-2 hashing algorithm. SHA-256 uses 64 rounds. The A to H are variables which compute a running sum. You will notice on each round the values in those 8 registers move to the right. The functions on the right S0, S1, t1, t2, maj, and ch are the functions which make up the SHA-2 algorithm.
The input (block) is broken into 16 32 bit words (w0 to 15) and used by the functions (S0, S1, t1, t2, maj, and ch) to compute a new value A. That is round #1. The same process happens 64 times.
The final set of registers A to H are then concatenated and that forms the hash.
