I'm a curly teen also, and I hate it when people try to change or correct my hair! I've been told by other kids to get a perm, but i like my natural curls. If YOU want it to be shiny, then i recommend going to target ( they have a wide variety) and getting a shine product. If you don't really care about how shiny it is then tell them that and move on. It's your hair!
Good luck!