what should i do

Question
i am 16 5'10 sophomore i wanna play running back what can i do to get faster stronger and bigger before next season

Answer
Thomas,
Hit the weight room and start running and conditioning.  Weight lifting is very important to build the muscle strength and mass you need.  Equally important is your muscle memory, endurance and ability to power run.  Talk to your school's strength coach or your football coach for a workout program.  Also your school's track coach can help  you with your speed and running.  You need to run at least 4 times a week and do speed drills and sprints 2-3 times a week if you are not running track.  You size will come with your natural growth and weight training.
Best of luck,