I need a diagram on a belt that help to spin the tub in the dryer . I took the belt off the back of the dryer and trying to remember how to put it back on.

Go the repairclinic.com and click on the "Repair Help" link. On the following page look for the "Dryer Belt Diagrams" link under the "Special Features" section. There is an extensive list of dryer belt diagrams for numerous makes and models. If this is a Whirlpool, refer to diagram H or K. If you aren't sure which diagram to use please post back with your complete model number (located on a nameplate around the door opening) and I'll explain. I hope this helps you.

Here you go... This should solv ethe mystery. See step 11 for routing.