This is a link to a basic InRoads fundamentals Manual:
http://www.aot.state.vt.us/CADDHelp/DownLoad/Standards/Manuals/VAOT_IFM_2007.pdf
This should give you an overview of the DTM how to create/edit Horizontal Geometry then Vertical Geometry, then define transverse geometry and put it all together create a proposed roadway model.
P.S. PowerCivl and InRoads should be the same once the products are open.