Explore the world of science and technology to find out what is most interesting to you. You can take classes in school on chemistry, astronomy, biology, physics, computer programming, electronics, etc. Read magazines, books, or web sites about science, technology, computer programs, or machines that seem exciting to you. Machines can be anything from cars to cell phones to airplanes to X-ray systems, etc.
You'll need a solid background in math to do engineering. If you wanted to create a 3D computer graphics program of a spaceship, you have to know how to calculate where to draw the spaceship nose and tail and all the parts in between, even as the spaceship zooms away, makes a sharp turn and zooms back overhead. I think this kind of stuff is pretty exciting. Sometimes I have to solve difficult problems, but I feel proud when I am successful. And engineers work in teams, so if you get stuck, someone will help you with ideas on how to get started again. Anyway, take the math classes.
See if you can meet some adult engineers who seem to have interesting engineer jobs, jobs that you think you'd like. Your parents could help. If you don't live near any places where engineers work, you might have to settle for email and photos. It's nice to know real live engineers. There are lots and lots of different engineering jobs, so it is good to know a lot about what kind of different jobs and companies there are out there, so that when you graduate as an engineer, you can pick a good employer and a job that is rewarding to you.
I work for Boeing in the flight simulation department. This is a huge computer program that can be used with the pilot controls and displays to simulate a real airplane. It looks like someone cut the nose with the pilot cockpit off of an airplane and stuck it in a room. You can look through the windows and see a projected scene of the airport or mountains or wherever you happen to be. All the controls, like the wheel and throttle, are real. It's like a giant video game. We have real pilots come and fly the simulator, and the engineers and pilots keep making improvements. The real airplane parts do the same thing as the simulated computer parts, so we can tell when it's ready to fly for the first time. I work on the 787 Dreamliner program. We are very excited and looking forward to the Dreamliner's first flight!
I hope that helps you get started. Explore the world (through classes, reading, people) to find examples of who you want to be, then work hard to get what you want!
Good luck, Alex!