Turn off the power supply from your dishwasher by turning off the power on your kitchen circuit breaker.
Open the dishwasher door and pull out the top rack all the way. Lift up the rack and then pull it more to remove it completely from the dishwasher.
Locate the upper spray arm at the top of the dishwasher, if there is already a spray arm that you need to replace.
Turn the upper spray arm counter-clockwise and pull it out of the unit. Insert the new upper spray arm part into the same position.
Turn the spray arm clockwise to lock it into place. Slide the top rack back into the dishwasher.
Close the dishwasher door and turn the power supply back on from the circuit breaker.