Watch heaps of rugby on T.V.
Watch it again.
And Again. Learn when to decide the right time to pass and to run at the gaps. Especially the gaps being a winger. For the gaps, here's hint: Always be conscious of where the forwards are when looking to break away.
Don't worry about muscles. Just focus on speed and aggression.
Smart Aggression is the key to being a stand out performer in rugby.

I Finished High School last year. The college I attended is currently the #1 Rugby School in NZ. De La Salle College.

Hey… I'm a 20 year old South African playing club rugby. Played wing and centre but now moved to flank.
It's true you should wait a couple years before using weights - wait for your body to develop a bit more (avoid injuries etc). For now though you should concentrate on core strength and fitness. To build strength do exercises that use your own body weight - push ups, pull ups, sit ups, squats etc. Don't neglect your stretches… Stretching for at least 10 minutes before and after your workout is essential for muscle recovery and to avoid muscle damage. Even though it looks dam nice to have a huge upper body the truth is that in rugby it's far more important to have strong legs.
Honestly though at your age, and because you play on the wing, I think fitness and agility is probably most important. If you continue to play rugby and get involved in games wherever possible your size and strength will increases naturally over the next couple years.
Good luck man…