Actors have a saying that I think aspiring scientists (and others) should internalize. Their saying is, "There are no small parts". You are still learning (we all are), but you are really really young, (like 1/4-1/3 my current age). A lab assistant is an early step in scientific development. I may not remember my history right but Faraday was once a lab assistant to Davy, (or the other way around). Anyway the point is well made in the example.
I worked in a biophysics lab one summer, as a lab assistant (I was a first year graduate student in physics and 25 years old (many years senior to your current age I assume) . My boss was a fifth-year graduate student in physics about to complete his doctorate (a much more senior but still a lab assistant). Next we had a post-doc researcher in our Lab. We were all under the direction of an Assistant Professor, and even his lab was associated with a more senior professor in physics. So you see there is quite a hierarchy involved. (By the way, I regard it as the best time of my life.)
Because you are in high school, it is important to do well in all the sciences (natural and social); languages, and whatever else you need to get into a college for more training and education. Like Choppy says, talk to teachers, counselors. If you can, even get input from counselors, faculty, or staff at local colleges.