Each canvas has several objects.
All objects of the canvas can be seen on the object list which is located on the top right corner of the canvas view.
You can also choose to collapse or expand it with the button that shows either an up or down arrow, and the option will be saved the next time you log in.
Clicking an object from the object view puts the object in the center of your current canvas view.
If you remember from our "Objects" tutorial, each object has its own order in its parent canvas. The higher the order, the higher the "priority" of an object to be displayed in the canvas, much in the same way that papers are arranged in a stack. To change the "order" of an object, simply drag the object's tab (inside of the object list), and drag it to the order that you want.
As a demonstration:
You can also right click it to see a list of options related to the object.