Do this outside. You are less likely to accidentally release a bedbug into your house, you are less likely to break a bulb, and if the contents of your luggage do happen to catch on fire then you are less likely to burn your house down.
Make sure the extension cord is unplugged. Plug the lights into the outlet inside the can. Then CAREFULLY lower your bulb-wrapped suitcase into the can, making sure you don't break any bulbs by doing so.
If you followed the alternative method at step 2, then you're going to place your extension cord at the part of the rim you bent earlier, so that you can put the lid on the unit with the cord under the rim.
It's OK if a few of the bulbs are not working DO NOT OPERATE THIS DEVICE WITH ANY BULBS THAT HAVE BROKEN GLASS.