I'm not an expert, I've only used it once. Try adding Architerra Hotspots around the perimeter of your AC fill that you will use to create the terain. Then select the fill and the outline tool. After you've done that, reselect the fill (that has now turned into an outline, but it still looks like your initial fill) and choose the terrain to turn the outline into a terrain. Try experimenting with the outlines as well by drawing them as a polyline, selecting them and then choosing the contour line tool.
the manual is very useful to print out and go through it.
I hope this can help you get started...