If you're just starting to learn, it will be hard at your age (no offence). There is already a lot of talent already out there with established portfolios and client bases.

With that said, definitely start locally, when your at a new restauraunt or somewhere ask if they have a website, if they don't tell them about yourself and ask if you can speak to the manager about making a website for them.

If you have another source of income, do a couple of sites for free for friends and such so you can easily get things into a portfolio that you can show to other potential paying clients.