Adding a Blank Canvas
When in the Page Tab, click on your page's name, then click on the three blue dots to the right of your page heading.
In the drop down menu that appears, choose to “Add Blank Canvas."
Drag the canvas into position in your page and adjust as you like.
Adding a Canvas from a Different Page or Design
When in the Page tab, click on your page's name, then click on the three blue dots to the right of your page's name.
In the drop down menu that appears, choose to “Add From Library."
Select a canvas from the designs you’ve created or from a design in the free Showit Library.
Drag the canvas into position in your page and adjust as you like.