Adding a shape is easy and versatile. They can be used as lines, borders, banners, headers, or a slew of other design elements. First hover over the bottom middle icon in Showit and choose the rectangle option to add the shape to your selected canvas.
Then you can add your shape and manipulate the shape sytle and effects options in the right sidebar according to your design needs, like so:
There is so much you can do with a simple shape! Hope this helps you in creating your perfect site, happy designing.