To use Handset Designer effectively, you need to become familiar with several windows. The most important window (and the one you will use the most) is the Drawing Page. The Drawing Page contains the drawing pages shown in individual Page Tabs at the bottom. The Shape Stencil pane contains the building shapes that you will use to create buildings as well as other useful shapes, such as dimensions.
You can add common shapes to a drawing by dragging and dropping shapes from the Stencil pane. (To drag and drop, hold your left mouse button down over the shape you want to add to your drawing, then move your mouse over the drawing while continuing to hold down the left mouse button. Once the shape is in place on the drawing, release the mouse button).
You can also use the options on the Geometry tab to draw common shapes by entering coordinates and other values.