can some1 plz respond to this and tell me where to find them or how to make them cuz i see ppl using them but i dont no wat they are...
c4d is a program that lets your create 3d abstract renders. they work very well for bg's. look in my sig, the bg is a c4d. its basically a type of GFX, like grunge, abstract, defaults etc.
You can find alot of them here on GR. Try the premium renders section for some great ones by community members, of do a search on DA. Also, I think there are some packs in the Resources section ^_^