And even if you don't know the Four in Hand, this knot is pretty simple: Over, Under, Around, and Through.
Step 1: Ready?
If you can't find a pre-formed Ascot, this style of tie will work with a thin scarf.
Unbutton your collar and a few buttons. Place the cloth around your neck, with one side slightly longer than the other.
Step 5: Through
You'll probably want to pull the sides of the top piece of cloth so that the Ascot is not too narrow.
Step 6: Tuck and Tighten
Move the knot upwards by grabbing the knot (under the top piece of fabric) and pulling it up, while you pull gently downwards on the back piece of fabric.
As you make the knot tighter, close buttons on your shirt until you achieve the look you want. You may choose to wear the ascot tightly, or to show a bit more skin around it.