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 circled bolts.
Clip the cable tie that holds the brake hose to the fork leg half way up.
Loosen the two clamp bolts on the side of the stem (the part the connects the handlebars to the fork)
Lift the stem off and leave the the bars/stem hanging. Be careful not to stress any cables/wires.
Lift off the headset spacers; there are 4x 10mm and 1x 5mm spacers.
Lift off the conical cover.
Pull the fork out the bottom of the frame. The headset might be impeding this; you have to tap the top of the steer tube to pop free the split ring on the top of the headset. Dont lose the compression wedge, upper race, dust shield and bearing that sit within/on top of the frame.
Grease both bearings and fit the lower one on top of the crown race on the fork. The ball bearing is directional; see this video for correct direction - 2:05 mark for headsets in https://www.youtube.com/watch?v=61Gygv82DAM.
Fit the steer tube through the headtube of the frame.
Now put the thin plastic dust shield on top of the upper bearing. Make sure its right side up.
Next put the upper bearing race on. The narrow/pointy side is down.
Fit the split ring on next with the narrow/pointy side down.
Fit the conical cover on next followed by the headset spacers. There should be 4x 10mm and 1x5mm spacers on the Omega.
Slide the stem over the top of the steer tube. Make sure the clamping bolts are loose enough not to cause binding. Push the stem all the way down and then install the compression bolt. Using a 5mm allen key tighten this bolt until it is snug. Proper tension of this bolt is important. You want to tighten it just enough so that the headset spacers will not spin when you attempt to turn them with two fingers. Too tight will hinder steering and wear bearings quickly, too loose and you feel a knocking/rocking motion under braking power or when riding.
HINT: It is often helpful to rock(wiggle/jostle) the stem/fork while tightening the compression bolt so that things fall into proper alignment. It is also best to do this adjustment with the bicycle resting both wheels on the ground. Rocking the bike is easiest by holding the front brake lever and pushing/pulling the handlebars.