You need to increase weight. You should add about 0.5-1 pound a week until Football Season. Get on a good diet with High-Protein and High-Carb with Moderate Fats. The nutrients should come from Clean foods like Chicken, Tuna, Oatmeal, fruits vergeatables, Almonds etc
Search these Training Programs
Rippetoes 5x5
Bigger, Faster, Stronger (I made a topic on this in the weight training section)
West-Side-For-Skinny Bastards
Theres tons of them.