The best resource in the world, at least for a starting point, is your local library. Ask for a book on propagating and it will open up a whole new world of gardening for you. And if that library can't help you, they are usually connected to a library consortium that will have access to the information you need.
If this is too slow for you, EXPERIMENT! It's fun, it's cheap, and you can really learn alot from both your successes and your failures.
In general, you can take softwood cuttings from a woody plant like holly, or you can air layer them. It should be very easy to get books that describe these techniques in detail. Some plants are touchier than others, but once you understand the"how to's", the fun begins!
I've never tried hollies--you do it and report your findings on the website.
My whole garden is a collection of plants from saved seeds, shared offsets, rooted cuttings, etc. I make it a point NOT to buy anything I can beg, borrow,or yes, I admit it, steal--but I only take enough to propagate.
Good luck with your holly, and many more hollies to come.
Diane Dodge, Ramsey County(MN) Extension Master Gardener