Can anyone tell me how to make fondant trees?

Maude, what kind of tree? Is it a freestanding tree on top of a cake or one that leans against a cake on the side? I have made a few & might be able to help you, have a look at my photo's & see if there is anything there that is similar to what you want.

I need the trees to stand up, needs to look like a forest.

. . . here is a tutorial that aine2 has done for trees . . .