If you want to create a pointy roof with 2 sides create a surface with the surface tool (2nd icon on the construction bar) Then click on the cornerpoints of this surface to get a menu where you can set an elevation. Set elevations for the 2 highest points. Check the 3D view to see what you are doing. For a roof with 2 sides you need 2 different surfaces.
If you want to create a pointy roof with 2 sides create a surface with the surface tool (2nd icon on the construction bar) Then click on the cornerpoints of this surface to get a menu where you can set an elevation. Set elevations for the 2 highest points. Check the 3D view to see what you are doing. For a roof with 2 sides you need 2 different surfaces.
We just made a tutorial on drawing an attic/roof: Drawing an Attic