1. Find the belt diagram. This is usually located on a sticker under the hood of your car, or in your owner's manual.
2. Identify the routing. The belt diagram will show you the path that the belt should take around the pulleys.
3. Start by routing the belt around the crankshaft pulley. This is the lowest pulley in the engine.
4. Follow the belt diagram to route the belt around the other pulleys. Make sure that the belt is properly seated in each pulley.
5. Adjust the tensioner. The tensioner is a device that keeps the belt tight. Follow the instructions in the owner's manual or on the belt diagram to adjust the tensioner.
6. Check the belt alignment. Make sure that the belt is aligned properly with all of the pulleys.
Once you have routed the belt and adjusted the tensioner, you can start the car. Check for any abnormal noises or vibrations. If you hear or feel anything unusual, stop the car and inspect the belt.