Airtrain is on the 3rd floor of T4, take Airtrain on track 1 marked "Jamaica Station". At Jamaica Station take the E subway to Roosevelt Ave/Jackson Hgts, transfer there to the inbound #7 subway to Queensboro Plaza, transfer there to the Astoria-bound N or Q subway to last stop-Ditmars Blvd. Airtrain cost is $5, subway cost is $2.25, you can purchase a regular pay-per-ride Metrocard at Jamaica Station for any amount and use as needed for Airtrain, subway or bus.
Airtrain is on the 3rd floor