I would suggest a full body fitness program. If you have gotten yourself a membership at a gym and are ready to go, then I would start strength training 2-4 days per week and doing cardio such as cycling, rowing, walking or jogging the same number of days as well. I would also suggest that you start with basic, compound exercises such as squats, push-ups, bent over row, tricep dips and crunches.
Here's what I mean, have a look at some full body work-out routines:
Try out one of the beginner programs and then select a few that you like that you can alternate between throughout the week. If you have any questions or concerns, feel free to e-mail me!