If it’s a Litter Maid (if it’s something else, you’ll have to find the manual or manufacturer’s website):
It will run a rake through the litter about 10 minutes after the cat uses the box. You don’t have to do anything to make it do that, except be sure it is plugged in or has batteries. There is a red light on the back of the litter box that will go out if neither of these is the case. The rake will scoop clumps into a plastic container at the front of the box.
If the rake keeps going back and forth, the problem is usually that the cats have made a big dune of litter against the back wall of the box. Take a litter box scoop and even out the litter.
Eventually, you will have to throw out the plastic container that catches the clumps, when it is full. How long this will take depends on the number of cats and what they’re fed. It should be a few days at least, unless there are a lot of cats. Be sure to put a new one in before the rake runs again, or it will scoop clumps onto the floor and make a truly unholy mess that you will have to clean up. There are adhesive charcoal filters that go in the diamond-shaped area on the underside of the top of the containers. There are clips on the litter box to hold the containers and their lids in place. Be sure that the litter container closes all the way, because the container isn’t in properly if it doesn’t.
You will eventually have to add more litter, too. There is a line on the inside of the box that says where the litter level should be. Be sure you don’t fill it too full, or the rake can’t handle it. And be sure to use clumping litter. It’s best in general to use whatever kind of litter the cats are used to, because cats generally dislike change.