Basically, you create a free account, then log on and you can create multiple coverage maps. Make note that elevations and heights are in meters, not feet. You can change a variety of parameters including frequency, type of antenna and even line loss.
I created a coverage map based on our current situation (as closely as I could guess) and it looks very accurate based on signal reports we've received. I put a link to the image on the "About Us" page in the discussion of the repeater.