Do you know a website or something about about teen nutrition?

Yes. www.healthychildren.org is a web site by pediatricians with information on nutrition for teens www.nutrition.gov/life-stages/adolescents/tweens-and-teens is a government website with information for teens. ( it is quite comprehensive_)
Yes.... It is more helpful if you are specific about what you want...You can google websites for teen nutrition and there are many...It depends on what you are seeking. Gain weight? Lose weight? General advice? Glad to help if you want to be more specific...