Okay, one other thing - do you have access to any equipment? (dumbbells, barbells, med ball, swiss ball, pullup bar, etc.)
Just a basic rundown:
For the first couple weeks I'd say that you should stick with bodyweight circuits just to let yourself get acclimated. Bodyweight squats, pushups, dips, inverted rows (
), pullups, burpees, and a few other exercises will allow you to get used to the work without too much resistance.
Since the season is rapidly approaching, it would be good to go with a concurrent/ conjugate training schedule. This means that you will be training strength, power, speed, and endurance qualities throughout the training period in order to develop across the board. More equipment means more options in terms of the exercises you can do during this phase.
And since you want to add a little weight, you definitely need to get your nutrition in order. Lots of protein and good fats plus veggies and fruits should be the base of your diet.