Super easy, and professional looking! I think they look perfect! <3 I think there's some problems with the uploader for the main images... so if they never pop up, i'm really sorry!
So get your cardboard piece, and cut a notch in it. The notch should be maybe 1/2 inch thick. It'll look kind of like the picture.
Put the thick ribbon under the cardboard, and fold the ends of the ribbon across each other.Fold the tails of the ribbon under, and use the bobby pins to hold the tails in place.
And yes, that is the butt of my cat. He likes helping me with these kinds of things by sleeping on my supplies.
Take the thin ribbon, and thread it through the hole between the fat ribbon and the notch in the cardboard. Thread it under and over, and then tie it tightly in a double knot.
Here's what it should look like in the back (which will be the front of the bow) after you trim the thin ribbon.
Un-pin the bobby pins, and trim the tails of the thick ribbon.
(Optional) Cut a triangle out of each edge to make them extra cute. And then, you're all done! Enjoy your perfect bow <3