Do what I did. Over the Summer holidays, I went gym 4-5 times a week. For benching, I would constantly work my way up to build strength. Always start at:
20kg - 30kg - 40kg and then push at your limit.
I started and my limit was 45kg. I would constantly work my way up then do 2 sets of 10 reps at 45kg. In 5 weeks, I had improved 25kg with benching. Don't do light weight high reps, do high weight and 8-10 reps each. Work slowly.
Remember, don't only work your arms, remember to maintain cardio and even work your legs, as you're a football player.
I usually lift with the team 5 days of the week. The head coach is always there so we have direction. We usually do a lot of footwork after we lift as-well.
Hmm, you're 120 at 6,0? Damn, i'm 15, 140pounds, 6ft.
I'm playing rugby and I can leg press like 300 pounds or so which is really easy. Bench about about 120 haven't done that in a while. Don't do squats or deadlifts.
My friend is pretty jacked...
He's 15, 5.11ft, and like 150-160 or something, he can bench 230 in reps of 10... Curls 50's in 1 hand like it's a 20. :/