data Structures / Hash functions

ok, let me start out by first sying that I'm not looking for any help doing my homework, but instead I need to understand the hashing function of data structures.

With the help of other members on this site, I have been supplied with links to good references, but for some reason I cannot grasp the concept of hashing.

For example I need to understand how to determine a hash address, and how to determine if a collision has occurred, and of course how to handle the collision.

My books are really not helping me, so i'm hoping that someone can either point me in a good direction of reading material, or explain to me what is going on.

Any help would be greatly appreciated.