The selector switch is held in place by two or more screws, remove the screws now. Disconnect one pair of wires and reconnect them to the new switch. NOTE: Only disconnect one pair of wires at a time. If you disconnect more than one pair without labeling the wires it may be very difficult to determine the proper sequence for connecting them to the new switch.
The wires are connected to the terminals with slip on connectors. Firmly pull the connector off of the terminal (do not pull the wire). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors for corrosion. If they are corroded they should be replaced.
When all the wires have been reconnected to the new switch, reinstall the switch and the interior panel. Plug in the dishwasher or restore the power and test the dishwasher.