First, There is a very small amount of electrical wiring that needs to be done. If you're uncomfortable or unsure how to hook up household electrical components, you should call for help from someone who is experienced to show you how, at least the first time!
These are the steps to installing ANY dishwasher in an existing space, in other words replacing an existing dishwasher:
1) Turn off the electrical power to the dishwasher at the breaker box.
2) Turn off the hot water supply under the sink that goes to the dishwasher, and removes the hose from the supply. Make sure that the hose can freely move out through the hole in the cabinet so that it leaves with the old machine.
3) Locate the screws that are holding the dishwasher into the cabinet. In most cases, there are 2 small screws up under the front of the counter, but sometimes they are screwed to the sides of the cabinet, but again, up near the countertop. Remove them!
***Note: I am told that some are screwed down to the floor near the rear feet instead.
4) On most dishwashers, there is a trim panel below the main dishwasher door. Behind that panel, there will be a small electrical box closed with a small screw. In there, the electrical connections are made, probably with wire nuts. Open the little box and loosen the wire nuts and disconnect the electrical. The ground may be screwed to the box or may be clamped together. Use your ingenuity in disconnecting . :)
5) Remove the drain hose from the side of the garbage disposer or the side of the drain above the trap if there is no disposal.
Slide the dishwasher out.
To install the new dishwasher
1) Install a NEW water supply line from the hot water supply under the sink and feed it into the dishwasher opening.
2) Ensure the wires are also in the correct space. You should probably prepare the electric wires at this time, to get them ready to be attached to some new wires. Cut the old ends off and strip back the insulation as appropriate.
Here is the secret! In the installation manual, there will be precise measurements as to where the channels are for the electric and the water supply. Following those measurements, TAPE THE WATER SUPPLY LINE AND THE ELECTRICAL SUPPLY DOWN TO THE FLOOR IN THE LOCATION INDICATED IN THE MANUAL. This step will save you at least 30 minutes and many cuss words trying to figure out how to fish water lines and electrical lines under your new dishwasher.
3) Slide in the new dishwasher halfway and feed the attached drain hose into the under the sink area, then continue sliding the dishwasher in as you pull the drain hose through the hole in the cabinet.
4) Hookup the drain hose to the side of the disposer or above the drain trap. The drain hose MUST be attached to the back of the cabinet at least at a certain height above the floor. This prevents dirty sink water from entering into the dishwasher through the drain hose. In fact, some localities require an air break on the top of the counter for the drain connection so check with the local inspector.
5) Make the water and electrical connections on the dishwasher.
6) Make your final position of the dishwasher, make sure that it is flush with the cabinets and then level the dishwasher as outlined in the manual.
7) Install the mounting screws that stabilize the dishwasher in the space.
That's it!