For the tax year 2018, you will have to file a nonresident return (1040NR) since you were on an F1 visa and are exempt from the Substantial Presence Test for 5 years. You can use our partner Sprintax site to fill form 1040NR.
In 2019 you will be able to meet the Substantial Presence Test (if you stay in the US for 183 days) since you changed your visa. And next year you should be able to file as a resident.
