You'll use shapes when you need a decorative graphical element that is simple enough and is not worth using specific software for, and when this shape doesn't have to receive any content.
The basic shape element of a layout is the rectangle. Chapter 7 will show you how to add more advanced shapes: in most cases simple shapes like rectangles and circles will be enough.
Pick the Insert Shape tool in the toolbar or press the S key. Draw a rectangle so that it covers the bottom half of the card. You can draw on the card if you want —remember the card will be cropped.
Tip
Shortcuts and Text Frame
Scribus uses simple keys (such as T, S, and I) when not in Edit mode.
When you're using keyboard shortcuts, verify that you're not in Content Edit mode. Otherwise, the key you'll press will be added to the frame content. One simple tip is to click on an empty place of the layout to deselect everything or pick the Select Item tool (arrow in the toolbar...