Weight lifting question.(URGENT)?

I'm 14 and I've spent this summer weight lifting at school. At my school we have phases of developmental workouts. I've been on phase 2 out of 3. Phase 2, since its just a developmental workout, it mainly comprises of squats, lunges, negatives (where we go back up instead of going down and resetting) lateral stabilizers, front stabilizers, push-ups and etc. Tomorrow I'll be testing to advance to phase 3. Phase 3 is actually weight lifting. When we test we usually go in groups and with a supervisor trainer. I'll be going by myself though. I'm pretty confident in the squats and stuff and the only thing I'm worried about is the 25 push ups and the negatives. Hence, I have a weak upper body. So I'm asking this question because I want to know if theres anything I can to do to make the push ups and negatives easier. Thanks. (Any advice is greatly appreciated) P.S. First year of weight training.