You need your 2018 AGI to efile 2019. The AGI is on 2018 1040 line 7. If you filed a Joint return you use the same AGI for each spouse. If you didn't file a 2018 return you enter 0 for the AGI.
Be sure to attach copies of your W2s and any 1099s that have withholding on them. You have to mail federal and state in separate envelopes because they go to different places. Get a tracking number from the post office when you mail them for proof of filing.