It's really easy to replace and you don't need any tools. The belt runs from the
PTO to the mower. Loop the belt around the
PTO pulley then bring it down. There are 2 pulley's mounted on the frame ahead of the front wheels. Make sure you get the belt twisted right on the pulleys and then back the pulley on the mower deck.
You might also want to try
Cub Cadet Landing Page. You may be able to download a manuel.
Hope this helps!
Michael