This is a new package. You are feeding them. They are building comb. Don't worry about attching this wax to the top bar of the frame. Put four rubberbands around the top and bottom bar of the frame. Cut the comb and rest it on the bottom bar of the frame, all the way to the side of the frame so that it touches the side-bar. Slide the rubber bands over the comb to hold it upright. By the way, the wax is probably too sift for an of this. If you can't salvage it, don't worry.
For your feeder set up....If you are going to put an empty box on top of a colony, you should probably fill the void space around the feeder with crumpled up paper of some kind. It's a void space in the cavity where the bees are building their home. It is natural for them to go as high as they can in the void, and start building. It would be simpler to get a division board feeder, or go with one of those screened feeder board covers like David Burns builds. That would allow you to use jars as gravity feeders in the top, but would not allow the bees to get into the box around the feeder.