I think the best way for you to realize the complexity behind it, is to take a look here: - http://www.grc.nasa.gov/WWW/K-12/rocket/shortr.html

With this you are only scratching the surface, so, as you can see, the journey is quite long. If the reading of the above links does not scare you, and instead, it pushes you to learn more, then you are probably on the right path. So learn, apply, fail, rinse and repeat.

You will also realize that electronics is, as well, an important component of a space company, so you will need to learn that too.