How can I set the pictures of a listing?

1. Click, in the header, on "Manage listings"
2. Find the listing's row and click on the icon as in the image
METHOD 1: photos from the gallery (read guide "How can I add pictures to the gallery?")
1. Check "Gallery", as pointed by the arrow; check the images you want to use (max 6).
2. Click on "Save selection"
METHOD 2: external images
1. Check "URL Adresses", as pointed by the arrow; fill in the fields with the URLs of the images you want to use.
2. Click on "Save selection"