I'm also 17, however I've been into web design for over 5 years(because I wanted to start a hockey card store way back when). The way I learned was looking through w3schools.com I'm a bad teacher but if you really want to learn how to design web sites hang around w3schools.com. Go onto Google and search for web design and html articles and learn everything you possibly can.
Test the water by creating a blog in the blogger.com. It is free. Learn the nuances step by step and when you are confident, start a full fledged website. Good luck