In MY INFO it asked you if you supported someone else. You should have said yes so that it would prompt you to enter the dependent. Click your name in MY INFO and go through the screens again.
Make sure you have entered your child as a dependent in My Info, and that you have entered the child's Social Security number. Careful— do not say that your child’s SSN is not valid for employment. If your child was born in 2023 make sure you said he lived with you the whole year. There is an oddly worded question that asks if the child paid over half their own support. Say NO to that question.