If you are eligible for earned income credit it is added automatically to line 27 of your Form 1040.
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-credits-deductions/qualifications-earned-income-credit-eic-eitc/L7w4BFP32_US_en_US?uid=m62rmz09
https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit/use-the-eitc-assistant
https://www.irs.gov/pub/irs-pdf/p596.pdf