If you have a roof that is an extrusion of a cross-section, then you would use the Section command. To use this command successfully, you first need to draw up the section in the Plan or Top view using the line drawing commands under Modify Roof > More, or under the CAD menu option.

After drawing the required section at full size, select the [Section] command. Then you are prompted to select the first line defining the roof section. Then you are prompted to select the next lines one after the other.  Keep in mind that each successive line must be joined to the previous line, so you will select them in order around the shape.

You can see in the diagram below, the cross sectional shape of the roof and the sequence of selecting the lines.

When you have finished, click the right mouse button. Then the Section defaults dialog box is displayed allowing you to enter parameters defining this roof.

Roof type Here you choose the category of material on this roof. It is one of Tiles, Shingle, Shakes Metal or Low-Slope.
Storey You can set the storey of the roof as 1, 2 etc. This makes it easier to separate the roofs making up each storey on screen. Also, various labour rates for estimating a roof can vary from one storey to the next.
Length The length of the roof. This is the amount the section will be effectively ‘extruded’.

When you click [OK], the roof is constructed by taking the geometry you created in the XY plane (the workspace) and projecting it along the defined length.

Here you see in plan view, the roof lines defining the new roof.

You can see better in ISO view (View > Select > Iso), what the roof is doing.

The two ends are automatically assigned as barges / rakes, and the internal lines are either ridges or valleys. The bottom edge lines are assigned as eaves.

If there are one or more arcs in the section profile, then the resultant roof is assumed to be a curve-quality roof, and its area will appear as Curved Roofing in the Tools > Tally-Quantities dialog box. To generate panels on such a roof, you must select curved quality material (even if the actual material is not in fact curve quality or high tensile).

To construct the curved roof, you must first draw the arc that defines the roof section, go to the menu item under CAD > Arc > Insert.

Then select Construct-Roof > Curved described in the previous section.