Can you make script to populate the scene

I am super lazy. I have a terrain GameObject which I want to have trees and bushes all over. Is there a way for me to just write a script simply write a script to populate a scene with prefabs and then store their locations so i can edit them? I don't even need to have them stored, it would be just as well if they were randomly placed every time the scene was loaded. I'm currently working in C#, but JavaScript would be just as well I suppose.

I might also mention that I'm learning as I go here. I have put a total of 1 hour into learning and about 10 hours doing stuff.

If you need to see my game, go to: https://goo.gl/aMWYeI and go MENU -> Downloads -> Sandboxes: Current Project

Thanks in advance.