im 15 almost 16 and play alot of rugby and i wanted to start going to the gym to get a bigger build just wondering if i do start going to the gym will i stunt my growth?
It won't stunt your growth at all - IF you use proper technique. Make sure you have someone, a trainer, show you how to properly lift and work out. It'll also reduce the chance of injuries.
Remember too, your body needs to rest occasionally. It's OK to take a day off. Your muscles actually "tear" and need time to heal - when they do they are stronger.
Watch your diet too - eat healthy. Your body will need extra proteins to grow.