In addition to all the awesome instructions from others below, a couple of pointers -
1. Use rubbing alcohol to wipe off the grease (I had no paint issues you might want to check in an inconspicuous corner first)
2. The connectors are stab type, so you need to use something skinny and rigid (I used one of those precision screw drivers) to push and hold in and wiggle the wire out of the old switch.
3. stab the wires into the new switch