To add a lamp:

  1. Click the Furnishing button on the toolbar.

    Or

    Choose Library→ Furnishing from the Window menu.

  2. Select the Lamps category in the pop-up menu
  3. Scroll through the thumbnails and drag a lamp into the 2D view.

Lamps must have a Glue by checkbox selected in the Object Properties tab in the Inspector. Set the lamps to stick to the ceiling (Glue to Top) or wall (Glue by Back). For lamps that stand on the floor or on a table, select the Glue by Bottom check box. By setting a Glue by checkbox you can move a lamp in 3D without detaching it from the selected surface.

Directions on how to change the luminosity or color of a lamp can be found in this KB article:

How to change the luminosity or color of a lamp. (KB028011)