Remove the front wheel.
remove the front fender.
Unbolt the front brake caliper from the fork. You first have to remove the caliper from the adapter (remove the two bolts indicated by arrows below) and then you remove the two bolts indicated by circles.

Clip the cable tie that holds the brake hose to the fork leg half way up.
Lift off the 3 headset spacers and the conical spacer below them.

Below that is a compression wedge, which is really important. Lift that off.

Pull the fork out the bottom of the frame.

Put new fork through the headtube of the frame.
Install the compression wedge with the sharp side down

Install the conical spacer on top followed by the headset spacers

Loosen the two clamp bolts on the side of the stem (the part the connects the handlebars to the fork)

Place the stem onto the newly exposed fork.
Peel back the rubber cover on the top of the stem, giving you access to the bolt.

Using The Long end of your 5 mm Allen wrench, tighten the bolt until it feels snug
With just two fingers attempt to rotate the spacers below the stem. You want the bolt tight enough that you cannot turn the spacers with 2 fingers. This creates the proper pressure on the bearings in the steering column. The goal here is to allow the handlebars to turn freely but without play.
Looking from above rotate the stem if needed until it is straight in relation to the fork.
Using an Allen wrench, tighten the two stem clamp bolts that you loosened in the beginning