Have you tried googling? There are a lot of pics of Knot gardens out there. Also check out the book on Topiary in the garden section of your local bookstores. If you search google or MSN you can see a lot of examples of Knot Garden designs, and some templates too.

My favorite Topiary book; The Complete Book of Topiary shows how they create the designs in the ground. It's simple but hard to explain in text, once you see the demo in a book it will make a lot of sense.

Good luck and post pics when you do it.

Just use a celtic knot and use this as a design.