when you have income from working, interest, or other investments you will receive statements from your employer, or banks etc. on how much you earned
as a minor you can file your tax return on those earnings and be eligible to use a limited amount of your standard deduction to reduce your gross income
you are not able to use your personal exemption because until you are 19 you are a dependent of your parents, and until age 24 if you continue in full time school
if you had only earnings from working and any amount of income tax was withheld you would want to file if the total earnings were $5700 or less because the withheld income tax would be refunded to you
there are other taxes on your pay stub(and W-2) which are not refundable, SS, Medicare, state disability etc.
you can see forms at www.irs.gov, and that would be a 1040EZ, 1040, all the schedules etc.