The tools for developing conceptual designs are all accessed from the ribbon, which changes depending on what is required to accomplish an action. For example, if you draw a rectangle and select it, 
Create Form becomes available. The Create Form tool allows you to instantly extrude the drawing and make it a solid or void form. See Ribbon.
If you then select a surface on the form, Divide Surface becomes available. This tool allows you to divide surface areas into buildable components. See Rationalizing Surfaces.
As you work on a conceptual design, you manipulate it directly in the drawing area, using several available controls. See Manipulating Forms.