I have a cake idea in mind, unfortunately I now have to think how I'm going to do it.
I want a pretty backdrop made out of gumpaste but have no clue how to stand it up, preferably I want into to be edible, my skills outside of edible materials are rubbish...

You can build a stand behind it out of gumpaste.

You know where you have a triangle that you glue to the bottom to use as a stand? I'm sure that isn't explaining it well.

no its explained perfectly, why didn't I think of it before lol thnx

You could also make a large rectangular piece and dry it on a piece of folded card board, so it has a bend in it. Then it would stand up on it's own. It would be a bit like an open book, but it wouldn't have to have a huge bend in it.