That is quite a long ride for the first day out! It is no wonder you hurt like hell.

You jumped in head first, but don't give up. If you hang in there, you'll soon be pedaling through that with ease.
The first days I had my bike, my legs would be wobbly after a three or five mile jaunt. Now I can blast through 20 miles without really breaking a sweat. Pace yourself as you ride. Get your heart rate up to a healthy aerobic rate, and let your cardiovascular system do it's job. Once you get into a rhythm, you will be traveling much faster than you thought possible.