Quick demo to show how to put on the zipper pants.

Step 1: Put pants on chair with the back hanging off the back of the seat. Unzip sides.
Step 2: Pull down the top of the pants
Step 3: Put down the underwear
Step 4: Sit on the chair
Step 5: Pull the waistband up between the legs
Step 6: Pull the pants all the way up and zip up the sides