Turn off power at the breaker
Confirm power is off with a voltage tester
Remove the switch plate cover
Unscrew the old switch
Pull the switch gently from the wall box
Take a photo of the wiring
Label the wires if needed
Loosen the terminal screws
Disconnect the wires
Connect the wires to the new switch
Attach the ground wire to the green screw
Tighten all terminal screws
Carefully tuck the wires into the wall box
Screw the new switch into place
Install the switch plate cover
Turn the power back on
Test the switch
Call a licensed electrician if unsure