I've always been curious about how to play...because I have a crapload of cards that I don't want to go to waste.
And I don't want massive huge monster-big answers to read like this if at all possible, I hate to read. (Though I will give you points for your effort if you do ;D)
Its a lot to explain in one answer. But the official Pokemon website provides tutorials to the TCG that can be found Here. The even provide video to help with the instructions, this is the site that help me understand it.