Stay with it and it will get there very quickly. I started with 8 miles in February 2009 and worked my way up to a century by July 2009, mostly doing my daily commute (8 miles in, 8-20 home depending on the route) with longer weekend rides. Weighed 360 when I started. Best advice I got was 2 days on, one day off. Don't over do it. But try to make yourself go a bit more than you did the last time each time you go out (either more distance or more hills).
You may hurt even more tomorrow walking around than you do today. Try to get on the bike for at least a couple of miles to loosen yourself up. The key (for me at least) at the beginning was to gut through the soreness and general rear pain to get myself to a point where my body acclimated to being on the bike and then it becomes normal fitness improvement/endurance building to extend rides.