When you first open the designer, the layouts panel is open on the left. Each layout is a standalone piece of content you can add to your email and change to meet your needs. If you are not sure what a particular layout is for, hover the mouse over it to find out what it is. Drag a layout from that panel into the main email design area in the middle of the screen. When you see a wide blue placeholder on-screen, you can release the mouse button to drop the layout there. See "Layouts" section below for more information on Layouts.