I need to do a cake for godsons. They are twins and want the Black and a White GI Joes. I am barely starting to decorate cakes. Could anybody help me with ideas.

First what type of cake are you looking at: Sheet, stacked, carved?
The possibilites are endless.
Sheet: You could do edible prints, frozen transfers, actual figurines with a detailed backdrop.
Stacked: Could use or make figures of them scaling a mountain or such.
Carved: Could carve on of their nifty tanks, or such.

The possibilites are endless, have you scrolled the galleries for any ideas?
Its a wonderful place to go for insperation.