First turn water off to faucet and remove the screw that hold's the handle in place. They may have a cap on the handle to remove to access the screw. After screw is out the handle should come off you may have to wiggle it a little to get it to come loose. Next you will have access to the spring and washer for that stem. It should be located on the bottom of the stem just remove it and replace new ones back in place. Some have sping's and seat in the body of the faucet if not located on the bottom of the stem.
Answers & Comments
First turn water off to faucet and remove the screw that hold's the handle in place. They may have a cap on the handle to remove to access the screw.
After screw is out the handle should come off you may have to wiggle it a little to get it to come loose. Next you will have access to the spring and washer for that stem.
It should be located on the bottom of the stem just remove it and replace new ones back in place.
Some have sping's and seat in the body of the faucet if not located on the bottom of the stem.