What are some ways of getting experience in Computer Science (an internship) before college without having prior knowledge on how to code and other sorts of knowledge relevant in the field?

I broke into this field when I was in high school. That was a long time ago: thirty turns of Moore's law ago. At that time there was no way for a high school student to afford a computer with 4K of memory, so I really needed an internship setup. I lucked out and got a fellowship in physiological computing from the American Heart Association, and worked on an early attempt to analyze EKG signals.

Now, you can go on ebay and get yourself the equipment you need (a five year old laptop with 8gb of RAM and a network interface) to develop whatever you want. You no longer need permission to do this kind of work.

You can download stunningly amazing programming tools, for free, including Eclipse and Visual Studio. Look for the so-called "community editions" of those tools. Do that. They are really, truly, free.

There are tons of tutorials online, from codecademy.com onward.

Create a web site to do something with a simple user interface but a nontrivial programming task. Then deploy that web site to either Amazon Web Services or Azure (they both offer free tier services to new users).

Here's a possibility: Display the time of sunrise and sunset for the user's location. That's an interesting problem. Why?

-- you'll have to do some research to figure out how to compute sunrise and sunset.
-- you'll have to figure out how to do those computations in your language of choice, be it Java, Python, or C#.
-- you'll need the user's location from the web browser. You'll need to figure that out too.
-- testing it will take some thought.

If you don't like that problem, choose something else. But don't choose something absurd like "a better version of gmail" or "a new operating system." Keep it simple.

Once you've done this and gotten it working, ask people you know this question, "If you could have a web site to do anything you wanted, what would it do?" If you get a good answer, get busy making that web site. If it's for a business maybe they'll let you call yourself their intern.

Learn how to use github.com to store your work product.

There: you have an internship and a way to get your portfolio of good stuff out there.

Look at

I would suggest targeting small to medium sized businesses, and/or offering to intern at no charge in exchange for the learning and experience you would hope to gain from an internship. Law offices and doctors offices could also be good placed to target. Keep in mind that the smaller the business, the more likely you would be expected to teach yourself vs. having people show you how to do things. The computer science field is pretty broad, so doing some self study to understand where you want to focus would be helpful. You could do something on the infrastructure side which could include setting up computers, networking, phones, servers, or on the database side where you setup the structure of the data, maintain it, report on the data, or on the application side where you write code. Help Desk or service desk jobs are considered entry level, so that could also be a place to start in a company that has a help desk.

Good luck and I hope this helps!