Go to your pool pump and drain your swimming pool. Follow the directions in your pump’s instruction manual. It may be as easy as flipping a switch to begin the drain. If you don't have an automatic pool pump, you'll need to siphon the water out with a garden hose. If you have diving equipment, you won't need to drain your pool.
Enter your pool once it's completely drained. Alternatively, if you having diving equipment you can put on your gear and enter the pool.
Go to the main drain at the bottom of the pool.
Unscrew the cover with a Phillips screwdriver, then lift off the cover.
Pull out the filter, if you have one, then clean out any debris inside of the main drain's bucket. If you're using diving equipment, use a pool vacuum to remove the debris.
Insert a new filter, if necessary, then line up the new cover.
Screw the new cover into place, exit the pool, then refill your pool.