Henry,
Although I am myself a hobbyist, color case hardening is an involved process that is generally ill suited to the vast majority of hobbyists. The investment in equipment is substantial--my custom built stainless steel crucible alone cost me over $300. And then you need a temperature controlled furnace or kiln, aerated quench tank, compressor, assortment of gunsmithing tools, solvents and boiling tanks, propane burners, buckets of wood and bone charcoal, protective clothing, etc.
For starters, I'd recommend Dr. Gaddy's article, which is linked below.
http://www.doublegunshop.com/doubleg...nal_v7i4_9.htm
Unfortunately, part 2 of his article is not on the internet to my knowledge, so you may need to find that back issue of DGJ to read it. If this is something that really interests you, I'd strongly suggest that you find a gunsmith in your area who does color case hardening and see if he will let you observe the process from start to finish. But whatever you do, never try to take short cuts with a torch and oil. That will not produce true case colors, no matter what anybody tells you, and may ruin the gun.