Hey man, all of this above is great advice, i just wanted to add a few points to use in addition to these.
In football specially, over all strength is not as important as power generated. The simplest way to put that is if you can grind out 225lbs on bench, thats strength. If you can blast it up fast as anything, thats power. Final numbers are important of course, but you should look into some methods of building explosion, which is a specialty of the WS4SB mentioned above.
Now something not many people mentionedin specifics: nutrition. You are going to hear many different things along the way, some will say keep it clean as possible, some guys are going to tell you eat 4 snickers bars a day. As someone who did the whole dirty bulk in high school and beginning of college and did it wrong and payed the price, my advice is eat real food as much as possible and throw in some treats now and then. fruit, veggies, meat, oatmeal, rice. If you are as small as you said, you should be able to throw that down no stop, make some real gains, and feel good doing it. Start 4 meals a day, expand as necessary. Dont be afraid to grab some pizza on the weekends or some wendy or BK, but your post workout meal shouldnt be in a drive thru every night. Ditch soda, any iced teas that arent diet or unsweetened, and if youre eating out and want a coke with dinner, grab a diet one. There will be people who will bug out and say never touch diet anything, but in jim wendlers words, its really not a big deal. Balance is the true way to succeed, so in terms of food, a 75/25 or 80/20 split of clean/dirty should get you big and strong as fuck.
Good luck next season man