For an example, Here's my pest control thread. http://www.sythe.org/showthread.php?p=6951749. Notice how all i did was give it a green gradient and just put Pest Control monsters in it.
If you have photoshop a good idea would to do like a rune ore-colored gradient and for all the parts in your thread (Introduction, General, Payment, Checkout etc etc) Put in a pic of someone mining ore from Tin - Rune or what have you.
If your confused how to remove the background from the person mining or how to do the gradient send me a PM or add my MSN in sig.