Welcome to The Guild. Check the Tutorials section for all sorts of step by step things to learn from. That's a sweet heightmap. We don't do a lot of that here because, well, most of us are poor and the free stuff only goes so big. If they ever made Maya for about $100 then there'd be a ton of them I did run your heightmap through a lighting effects filter and a gradient map in PS just to see what it looked like. Pretty cool.