I learned to make them with this tutorial, though I switched up the measurements a bit for my own.
First, a strip of felt. I used cheap craft felt, in a 9" x 1" strip.
Next, find the middle of your strip, and then fold it back onto itself into a sandwich.
It's important to keep both sides as even as possible! Pin down the edges once you even everything out.
Now, place a dot of glue on each flap and press it down into the middle.
Once the middle is glued in place, cut a small 1/2" strip of felt and place it underneath the middle.
Glue each side of the 1/2" strip to the center of the main strip. This will create the middle of the bow!