skinning help

[T4IS3R#39]

alright so when i put the graphic on my bike and i want to turn it on a bit of an angle it doesnt work. i am using gimp and i was wondering if anyone can help me with this cause its making me really frustrated. none of the tools that turn or flip or anything work. they just make a box come up in the side and if you chane the numbers or anything and click rotate or whatever it says, then it doesnt do anything. anyway i just want to know how to turn the graphic on a bit of an angle