Math. Calculus 1-3, linear algebra, and differential equations, especially. If you figure out where you're going to go to school, figure out what their main programming language is (this may differ by department, so you want the one Computer Engineering uses) and get started learning it. Physics with calculus may also be useful, depending on exactly what you want to do with your CpE degree. Those are the basic building blocks, really.
If you want to see a little more of what you're getting into, pick up a book on digital logic and/or computer architecture. That'll help you pick up boolean algebra and number systems, among other things. Also, circuits/electronics analysis and design.
My advice would be to think hard about what you're doing. I went into computer engineering thinking that I would get a job designing hardware (Intel, nVidia, etc). That was what I wanted to do. At a certain point (probably in the middle of Circuits II or electronics), I realized that I didn't like hardware design all that much and focused on programming, robotics, and embedded systems. It's possible that I would have been better off in Computer Science. So if you're thinking about this because you like programming, you may want to rethink. If you're really in it for the hardware (and it sounds like you are), then I wish you the best of luck.
Also: Work on your writing. I know this is a forum, and you could well be posting from a phone, but your writing doesn't look all that great. It is important that you can form proper sentences. As much as I hated it, I had several English classes, some literature classes, more Liberal Arts classes, and had to write all sorts of reports as well. So whether you can write or not, be prepared to do so. It'll also make the people who have to grade reports not hate you.
<-- Graduated with a BS and MS in Computer Engineering from Clemson University.