Disconnect the power at the circuit breaker.
Disconnect the drain tap from the waste discharge and disconnect the dishwasher drain if there's one connected.
Insert the wrench that came with the garbage disposal into the mounting lug just above the main body of the old appliance. The appliance will drop out.
Turn the appliance over and remove the electrical wiring---it's usually below a plate.
Disconnect the electrical wires from the supply.
Knock out the drain plug on the new appliance and remove the plug from the inside.
Knock out the inlet for connecting the dishwasher, if you will be using one.
Reattach the wires by removing the electrical plate and attaching the cable you removed from the previous install. Try to re-use existing parts, such as the cable connector. Then replace the plate.
Slide the flange over the discharge tube--including the gaskets. Secure with the included bolts.
Hang the appliance by aligning the mounting tabs on the mounting ring.
Rotate the disposal so that the discharge tube is aligned with the drain tab and reconnect all of the plumbing, including dishwasher.
Reconnect the wiring at the wall-side.
Fill the sink with water and test.