All layers which you added to design are displayed on Layers tab.
To change the order of layers, just follow ways to do that.To back or forward other layers, just drag and drop them.
Change from Layers tab
Go to Layers tab, change the order of layers from top to bottom to sort them, just drag and drop them to change position
Change from toolbar
Select a layer via design area, click on Arrange Layers icon on the toolbar then change on Backward or Forward to move the current layer to the front of to back of another one.