Get yourself a copy of the Lyman 48th edition Reloading Handbook.
It's an excellent reference for beginners, has some good tips for advanced loaders, and has a truly fabulous assortment of loads for even some of the more esoteric cartridges.
One piece of advice I'd give you. Find something else to load for first. "Gas guns" like the AR15, M14, etc are very picky about what they'll reliably digest. Semiautos can be very pressure curve sensitive. It's not a good place to start as a beginner and you may well find yourself frustrated quickly or damaging your rifle.
Get yourself a cheap .38 revolver and start loading .38 Special. It's a cartridge that's very forgiving on beginning reloaders. Barring that, find yourself a bolt action .223 rifle and use that to test your loads. Don't start reloading for a semiauto rifle until you're more familiar with reloading.
Oh.... and get the thought of saving money on ammo with reloading. You'll quickly find that bulk surplus ammo is cheaper than what you can load. Found that out myself with my M1A. The only loading I do for it, is with ammo that I need for accuracy. Even then, if I factor in all my case prep and reloading time and assign even a minimal dollar amount to my time, it's probably still cheaper for me to buy Black Hills or even Federal Match ammo.
