Where would a 15-year-old teenager be able to find a job or internship in computers?

Considering the area that you live in, you can send an email or even a phone call to a local technology company outlining your interest to work for them. At your age, you probably do not have much experience, so be prepared for unpaid or even low paid internships. But even if it is unpaid, think of it this way, the experience you are investing in will pay off in the long run. The most important thing is to not give up, emphasize your willingness to work and your enthusiasm, and companies will be willing to take you for an internship.