Okay, because lots (and I mean lots) of people were nagging me about how you work this, I'm putting this here. Thanks, @Scizor11 , about being polite and suggesting to put this here. Watch the grass scroll over everything (that's the loading screen), press space... Buildings - Click up/down keys to change. Click once to drag it. Click again to drop it. Stamp button to stamp.
thanks to d610