[Definition of a Tax Noob] Do I need to File a Tax Return for Selling/Owning shares of Stock if I don't have to file a Tax Return?

Hey all, first off, I'm not sure if this is the correct subreddit to ask a tax question. Secondly, I'm a 100% tax noob. I'm a full-time student, and in 2016 I've began investing (specifically on Robinhood), mostly for fun and practice (my account is worth around $250). I have taken the IRS tool to see if I have to file a tax return for 2016, and it said I do not. It didn't ask for any investments or trades, that I'm aware of, though. I have my Robinhood tax documents form, if I need it. Any help is welcome. I just want to try to make sure I'm doing what I'm supposed to.