How should I switch over to playing guard?

I'm 14 years old and 6 foot 2. i normally play forward and have a great jumpshot. I played in a game with my travel team agaisnt a highschool team where i scored 18 points and my coach said that i need to learn how to play guard. He basically said look your a great player and you could be 6 foot 5 and play post at a small school, but you need to learn how to play guard, because if you do that you have the work ethic and skills to play at a really high level. so how do I go about playing and training like a guard?