Personally, I am an undergraduate mathematics major. As you can see, I haven't answered (or even asked) many questions on this site. Most of the questions that I can answer get closed before I can answer them.
However, I don't think I am a typical MSE user. Judging by the sophistication of the questions on this site, I would guess that most MSE users are either graduate students or professional research mathematicians. But I could be totally wrong. There are a fair amount of questions from high schoolers or undergraduates as well.
Congratulations on taking calculus as a high school freshman! If you follow the calculus tag, you may find some questions that you can answer. However, most of the questions on this site are probably well above your current level. If you really want to be able to answer questions on MSE, then you've got a lot of studying to do.
May I recommend some resources to get you started (in no particular order):