Ok, this is how I think it should go. After you connect a piece of cord (with the plug) to one end of the first strip of flexwatt using the connectors and insulators, you will need to take a short piece of cord(with both ends stripped) and connect it to the other end of the same piece of Flexwatt. Now take the other end of the stripped cord and connect that to the end of the 2nd strip of Flexwatt. Then you take and connect a piece of cord the the other end of the 2nd piece of Flexwatt and run that down (or up) to the next Flexwatt on the next shelf and repeat this till done. Then put some electrical tape on the ends of the very last piece of Flexwatt to prevent any shocks. Then plug it into your thermostat and check all pieces of Flexwatt and make sure all are heating up.
You will only need one thermostat if all shelves are going to be at the same temp. You are going to need a lot of connectors and insulators, I believe 4 pairs per shelf! Anyone please correct me if I got anything wrong here!

Hope this helps,

Dave