As a teenager you can earn some online money by taking online surveys through surveryjunkie or inboxdollars.
You could also look on freelancer to find freelance jobs that you're good at doing and people will pay you to do those jobs for them.
You could also start up a blog now and work to build the content on it and build up traffic overtime and by the time you turn 18 or older you could be making some good money through Adsense or other networks from your blog.
Making money from a website or blog takes time though and won't happen overnight so be prepared to work on your blog for a minimum of 5 years before making a good amount of money from the blog.
SEO and website traffic takes time to build up, but if you don't give up on the blog and keep working on it over the years it can make you some good money and even a full time income in the future.