To place square like that, I would suggest looking at how other squares are placed. For example, in the folder 'graphics' under 'pictures' you find 'bagSel.png'. This is the kind of square you're looking for, right? See how it is used, and try to copy that.
Ps. I have no experience with this thing at all (so I'm like a Ralts without Confusion, just growling about...)
EDIT: Oh wait, I think I misunderstood your question. You want information in those circle-thingies. Uhm. I can see that there is information displayed. Maybe try to find out how that is displayed, then copy the code for that, and display the name and quantity instead. The name is (I think) already a string (text-variable), so you can just display it. As for the quantity, that will probably be an integer (number-variable). You may have to cast it (but I don't know how that works in Ruby).