Since I already had taxes withheld from my paychecks, do I need to file a tax return?

Yes, you should still file a tax return. The U.S. tax system is a “pay as you go” one, where taxes are withheld from your paychecks as you receive them (based on information you gave your employer at the time of hire). You should file a federal and/or a state income tax return to determine if you paid too much tax and are due a refund, or if you did not pay enough and owe tax.