You want to eat a bunch of carbs today so your body have time to store glycogen for tomorrow. I like a big plate of spaghetti and it really does help. For tomorrows breakfast you can eat about anything you want. I like oatmeal and toast because it's easy on the stomach. On long rides I have been eating Good and Plenty, it contains carbs and sugar and no fat. You want to take a sip of water every 15 - 20 min to stay hydrated. You want to pedal with a high cadence and a lite pressure on the pedals, that will keep your legs from getting tired. It's not a race so take your time and have fun.