Getting or Updating Your Passport
Both people who wish to stay in the U.S., and people who wish to move with their parent/guardian, need a passport. The issue is, assuming you are under 16 years old, you'll need to show parental consent, which can be tricky, because if your parents are undocumented and go help you with your passport, they may be concerned about potentially revealing their own undocumented immigration status.
Here is a link with information on how to get a passport when you are under the age of 16, which includes, among other things, information on how to get a passport when your parents cannot come with you to apply for it. See travel.state.gov. This is something you also might wish to discuss with an attorney or one of the reputable immigrant rights organizations that provides assistance to mixed status families like yours.
Regardless of your approach, you will need to bring proof of your own citizenship - the travel.state.gov website provides details about what you need to bring, including the specific ways you can prove your citizenship and eligibility for a US passport.