Be sure to shut off water to faucet.  After you remove the screw, carefully pull handle straight up.  You may have to wedge a screw driver between the handle and the base but pry so that the handle comes straight up.  Once the handle is removed, you will have to loosen the spanner ring that holds down the shut off valve assembly (which was what was leaking on my faucet).  You will need to replace the whole valve assembly.   If you don't have replacement parts, you can call Pegasus at 1-877-580-5682, give them the model number and they will help you.  The spanner ring can be removed by using large needle nose plyers in two of the slots, but be sure not to damage the threads - just firmly hold the needle points in the slots and turn CCW.