Is there a way to place an image on top of an image?

Basically what I am trying to do is place a background image into dimensions, then place another image that is much smaller on top of my background image and place it on one of the walls of the background image to make it appear as a canvas print on the wall, but can't figure it out (Very new to dimensions, just downloaded it tonight). I've done it in photoshop and looks good, but just wanted to try it out in dimensions to see if it made it look nicer.