I need help with Photo Shop?

I would like to take a picture for an album cover.. I want to be standing with a guitar in front of a lot of autumn trees.. however.. all of the leaves have fallen.. If I stand in front of a bunch of trees which have no leaves on them, is there a way I can put leaves on them.. They don't have to look in fine detail real by any means.. in fact.. I think it would look cool to mix both real trees with faker looking leaves.. along with adding leaves.. can I add blue to their color and purple? Any suggestions would really help.. thank you :)