Sharpevil

Hi, I'm 19 now, and I've gotten by through most of my life on my quick metabolism. I've always eaten whatever I wanted, and never really put on weight. I've never had much muscle either, but that didn't bother me much. I've gotten by on little-to-no exercise save for high school marching band. Now, though, I'm starting to get a bit of a gut and I've got some pretty severe insomnia, so it seems to be pretty vital that I start exercising. I won't have access to a gym until the fall when I head back to college, so for now I'm limited to a bicycle and household objects.

So, can anyone recommend or help me build a routine? I've been biking for 45 minutes every day for about half a week, but I figure I need to vary it more. I'm looking more to get fit than 'get big'. I would like to build my abdominals, though, since my stomach seems to be where all my fat is going. I'd like to get it before it begins to sag down and become flab.

Information, if it helps any -
Height - 6'4" (I'm tall)
Weight - 190 lbs (Not quite sure where that all is. Pretty sure it's not muscle, but I still look pretty skinny.)

Anyway, help of any sort is appreciated! If there's any more info that'll help me make the most of this, I'd be happy to answer.

Thanks!