I'm Viansa, a summer HS intern at CareerVillage.org! When I was told I wouldn't be able to find any summer internship because my parents didn't have any connections in the tech industry, I was almost discouraged from trying to obtain an internship. Don't be! Persistence is going to be key for finding an internship.
First, I would create a resume of all the valuable experiences you had. I didn't attend any formal interviews for my internships, because my resume covered all my experience. Make sure to include a project or work you're proud of. Don't be afraid to include anything, or think something is not worth including, your future employers just want to make sure that you are a responsible student and willing to learn.
Next, figure out what kind of internship you want, and in what industry. Startups and smaller companies are a great bet, but companies such as Intel and Google both have summer internships. Different professors at your local university would surely be interested in an intern. Do you want to fill out an application for your internship, or email several companies and hope for a call back? Both are valid options. My local hospital has internships/volunteering over the summer. There are so many opportunities! Make sure that you aren't shy about reaching out to people. I emailed several companies before I got an internship, and none of them were listed as an official intern position or had a "HELP WANTED" sign; I just asked if they could use a summer HS intern for about 5-6 weeks.
Viansa recommends the following next steps:
It's great that you want to gain hands-on experience as a high school student. There are many internship opportunities available for high schoolers. I got mine through the Academy of Finance, a high school program that prepares students for careers in business. Reach out to your school to see if there are similar opportunities. Alternatively, LinkedIn is a great platform for finding internship opportunities!