How can i tell a friend how much i appreciate him?

I'm 16 too, and I just told my best friend that I care about him. I always go over to his house or he comes to mine, and we always hang out. It's sometimes difficult for us guys to express our appreciation for someone, but when I really wanted to, I just went up to him, and told him that I'm always thankful that he's always there for me, and that I'll be there in exchange. If you say it straightforward, it can be kind of awkward after, but something like that could really get the point across without making a scene. Hope this helps!