What are you trying to do? You cannot use the current online software for a 2018 tax return--and you say you had not income for 2018, so there is nothing you need to do in regard to 2018.
The current online software is only for a 2019 return--no other year. Do you have income to enter for 2019?
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If you are a full time, unmarried, student, over age 23, and are not claimed as a dependent by someone else (e.g. your parent) you may be eligible for the up to $1000 refundable American Opportunity (tuition) Credit (AOTC). That credit is not dependent on having either kids or earned income. You must be at least a half time undergraduate student. There's even a loop hole available to claim the credit, if you are on scholarship.
If you are less than full time, and not a dependent, the over age 23 restriction does not apply.