Here is a really quick Instructable on how to replace a slingshot band
Step 1: Wet the Ends
Wet the ends of the bands with rubbing alcohol or just plain water. It will make it easier to put on.
Step 2: Slide It On
Slide the band onto the slingshot and end at the bottom of the curve.
Now wait 24 hours for the water to dry so it stays on.
SteveS251 made it!