Usually your city or town will have that type of info. Many times it can be found and even downloaded from your city's website. Also, contractors in your area (or at least their office personnel) should be able to steer you in the right direction. I just re-roofed my house and some of the best info I got was from THIS website. You can also get some info from Owens Corning, IKO, and other roof manufacturers from their websites.
And, when you get to the point of buying your shingles, be sure to retain at least one of the wrappers, and read it thoroughly. The manufacturer's provide a lot of useful information there, including cutting the starters and caps, how to start your rows, etc., but, unfortunately, a lot of people seem to ignore them, and then find themselves stymied, when the anser is right in front of them.