Slice bagels in half, if needed, and lay them on your baking sheet with the inside facing up.
If pre-baking bagels: Bake bagels on one side for approximately 5 minutes, then turn over and bake the bottom sides for about 3 minutes. (Timing, of course, depends on how much of a crunch you prefer.)
Spread desired amount of pizza sauce on each half bagel.
Top each bagel with cheese and then add any other toppings you prefer.
Bake 8-10 minutes, until cheese is melted and browned as desired.