I was in high school when I started CS (now a junior in college) and if there is one thing I would suggest is not to go for the internship this early. Not only is he/she going to have to settle on an ok to subpar internship because of his/her age, but he/she is also going to never have more free time than now to create some kind of business on their own. In this time, I would experiment with different business ideas and try to start something awesome. Something that helps people solve problems.

I love CS, but I am the type that more than anything wants to build a company and help people. I understand if he/she is not the same way, but if I would have recommend not jumping into the workforce so immediately.

The day quickly approaches where I have to make a decision to either start my own thing or get a job somewhere. A job takes a majority of your time which would really put a damper on my dream. There are stories of people doing both, but if it happened all the time, it wouldn't be a story. I'm not using that as an excuse, I am using it to bring home the point to enjoy and take advantage of the time you currently have without responsibilities.

Bottom line is have fun. Experiment with different ideas. Try to make something cool that people want. There are more than enough resources to get started. Just do it.