You can upload many images to the Design Labs. You don't need to only use 1 image. This is helpful if you'd like to layer images to create your final design.
Important: When working with multiple images, you will need to use .png format images. PNG's have the background removed so they can be layered without interfering with the image under/over it.
To change the order of your layers, click and hold the double line symbol in the top left corner of the Image box. The cursor will turn to a hand and you can now drag the box to it's new position.