Check out the fan example to understand how it works
Sorry, I'm not sure if I did this link right, I guess I'll see in a minute. Anyway, I think the pictures and examples make it pretty easy to understand the basic concept of what a torque converter does and how it works. I saw the fan example a few years ago in a book and I think the analogy works pretty well. http://www.3dauto.com/module/transmission/1197/
Here's a longer version that goes into a little more detail but for some reason they don't have any pictures. So, I guess take your pick. Anyway, good luck I hope this helps. http://www.3dauto.com/viewterm/2735/