The front brakes on your car do most of the work, often about 70% of the braking force.
Replacing the pads is one of the simplest ways to keep your front brakes working effectively.
Learn how here. Please keep in mind that brake fluid is corrosive to paint so try to keep it from getting on your car's paint. Be sure to rinse it off if any does land on your paint.
When replacing your front pads, be sure to check your rotors for excess wear. If necessary, have the rotor re-surface or replace the rotor along with the pads.