Treadmill Script

Hello everyone. I'm pretty new to scripting and I've only recently began making games. The process has been going smoothly so far, but I am stumped on trying to make a treadmill. I'm not sure how to make it so that the part on the treadmill works. This is what I tried:

I didn't know how to make the treadmill move backwards, so i figured I could stop the player from moving, but that didn't work the way I expected lol. Can anyone help?