If you order the flexwatt from RBI, there is an option to have it already wired and completely assembled/ready to plug into your T-Stat. It gives instructions on how to order it that way on the website. I think you have to add a clipset/cord option and leave instructions. I bought two- two foot long pieces of 11 inch flexwatt to use in incubators and ordered this option. Just taped the heat tape down and plugged it in.

As for how you attach it to a thermostat, the thermostat has a probe that will go on the flexwatt, and the flexwatt plugs right into the thermostat. (Or into a power strip plugged into the thermostat if you are running more than one heating element off the same t-stat.