Firstly, position your tie so that the wider end of the tie is on the right and the thinner end is on your left.  You should aim to have the tip of the thinner end resting somewhere just above your navel.
Grab the wider end and place it over the thinner end to the left.
Take that wider end and loop underneath, then bring up into a neck loop.

Bring the wider end down to the left.
Loop the wider end over to the right, from underneath.

Bring the wider end up to the center, towards the neck loop you have formed.
 

Take the wider end over the neck loop and down to the right.

Bring the wider end across the front, to the left.

Take the wider end and thread it up from underneath.

Bring the wider end down and into the loop you’ve just created.

Tighten the knot by pulling down on the wide end, slide the knot up and adjust as needed.