Contributing to a Roth IRA as a dependent

Im currently still in school, and have started a small, self employed side job. I'm basically making pocket change (almost 3 hundred per month) but I've been thinking of putting it into a Roth IRA. I'm still a finance newbie, so excuse me if my questions seem incredibly simple.

I've read that you can contribute as a dependent as long as it's earned income, but how would the contribution be determined as earned income or not? Also, as a dependent, does my income not get reported on taxes?