Well, like Pierini says, Crossfit is really great for conditioning, but if you jump straight into it from having not really done anything, you might just about kill yourself. It's very intense, hard work. I think it would be a good idea to start with a basic bodybuilding-type routine for a month or two, with lots of running both for distance and sprints for conditioning. Like for instance...
You can't go wrong by doing basic, full-body exercises
- stick to this list: squats, deadlifts, bench press, overhead press
, bent-over rows, pullups (if possible - if you can't do them, try jumping up and going down slowly as possible), cleans, dips, lunges.
Try mixing in as much running as you can - maybe run for 30 seconds, then walk a minute, repeat for 30 minutes. After that starts to suck a little less, run a minute & walk a minute. Then run a minute & walk 30 seconds. Eventually get to the point where you keep running for the entire 30 seconds. When I started 3 or 4 years ago, I took about 2 months to get to the point of actually still going for a whole 30 minutes without stopping - I remember the day and man I was proud about it. If you can handle it already, just jump in and start running 3 miles at a time, or series of sprints.
Monday - squat, bench press, clean
Tuesday - run 5k
Wednesday - deadlift, overhead press, pullups
Thursday - rest
Friday - run 6 400 meter sprints, fast as possible, rest 2 minutes in between
Saturday - bent over row, dips, lunges
Sunday - run 10 100 meter sprints, fast as possible, rest 2 minutes in between
Monday - rest
Tuesday - repeat from the previous Monday.
As another option, you may want to peruse this page:
It has a basic program which is designed to help deconditioned people get up to speed gradually. Could be just the thing for you.