To add images to the buttons on your menu, you need to login to Web Admin then go to HQ Food & Drinks -> Item Details -> Item Images.
Next you would click Edit under the section you want the image to show, POS (on the iPads), Mobile (Online menu) or Kiosk.
The image will need to be small, 240X120 pixels, after you hit edit you hit Choose File and select the image you want to use.
Hit save, and then you are done!