The Half-Windsor is a bit smaller than the normal Windsor and easier to do. It makes a slightly asymmetric triangular knot of medium size that is still suitable for formal events. The knot looks good on all types of collars including an open-collar and is ideal for wider ties of light and medium fabrics.
What you see in the picture is your mirror reflection: you will see the same picture if you stand in front of the mirror. Drape the tie over your neck with the wide end on your right. The narrow end should be about a foot long.
Cross the wide end over the narrow end.
Bring the wide end under the narrow end to the right. Pull the knot tight after every step to prevent it from working loose.
Pass the wide end through the loop around your neck from above to the left.
Bring the wide end over the narrow end to the right.
Pass the wide end between the collar and the knot from beneath.
Pass the wide end downward through the loop it has formed. Tighten and shape the knot.
Adjust the position of the knot, holding it with one hand and pulling the narrow end with the other.
The Half-Windsor knot is complete!