Use the screwdrivers to remove the screws in the rear access panel of the washer and then pull off the panel.
Locate the pump coupling, which is the rubber part that connects the motor to the water pump, and unscrew the clamps securing it to the motor. Once the coupling is removed, tension is removed from the belt.
Slide the belt off of the pulley assemblies and slide the new belt in its stead. Reattach the coupling with the mounting clamps and check the tension on the belt. You should be able to wiggle the belt a bit, but not more than an inch or so.
Close the access panel and turn on the machine. Run it through a cycle while observing it to see how it handles the belt change.