Now that you have learned how to remove the pulley face in Part 2, you will now be able to install a new fan belt. The fan belt is tightened or loosened by inserting a certain number of shims in between the pulley. Now, obviously that the fan belt is new you will use a different amount of shims than you had on previously.
The more shims you add the looser it will be, so you should guess how many you need and keep removing or adding until you get the right amount of tension. If you are simply tightening a slackened fan belt you should start by removing 2 shims.
Once you have figured out how many shims you need, simply replace the extra shims underneath the nut where they are stored, and replace the cover, nut and pulley face. Insert the screwdriver into the notch again and tighten the nut with your ratchet. Once again test the belt and make sure that it only gives about half an inch of flex.