You can use a service like Cafe Press, though I have never used them myself. I have had T-shirts printed using Stellar Designs, a graphic design and printing shop, here in the city where I live. All I did was bring them my artwork, a sketch I penciled on a piece of paper. They did the rest. I called around several places before I settled on them. You can do the same. Just look in your local phone book.
Go to an art supply store and ask them how to do silk screening (it is really easy; the kit costs about $50).You really need a trained silk screener to show you how to do it (that s why you should not just buy a kit off the internet)
I would suggest going to the Small Business Association (it is free) for help figuring out a business plan if you really plan to make some money at this. It will take a little more planning, but you will be ahead in the long run.
