I would assume that it is going to be 3M double sided tape that you would use to reattach it. Remove all the reside that is currently on the computer right now that was left over from the HD reinstall, then use double sided tape/adhesive to reattach it. Apple doesn't use glue for their glass but double sided tape. You can probably pick some up at a hardware store or off amazon.com. I would recommend not getting a kit if there is one, most of the times they are "pre" cut, but the will never fit. Instead, get a big role and cut it yourself, making sure that the tape will never cover or attach to any cables/camera/antennas. If you do this, you should not have a very hard time reattaching the display. I use 3M double sided tape for iPods, iPads, and MacBook Pros, and it sticks well.
Hope this Helps