Neu, are you looking to be in shape or do you want to competitive as well ?
If in shape, I'd start with 45 minutes on the bike, then after 3 rides/week, bump it up to 1:15 hrs, then after 3 rides/week go to 2 hours/ride for 3 times a week. More than anything, make sure you eat well too while you're doing all of this. (that means cutting back on beer and other dead calories)
If you want strength or if you have time, some sessions with weight would make a big difference. You can do simple exercises to build your core (abdominal twist, pull ups, jumping jacks) and build that into your training. If you want a smooth pedal stroke, do some specific trainer exercises like pedaling one leg at a time while the other is unclipped, etc....