First you have to know what terminal is your international flight , then you go to the airtrain area check the I formation board the airtrain will keep you informed on each terminal stop , so just listen for your stop get off an make you way to your check in
There are shuttle buses that will get you from terminal To Terminal, but keep in mind they run on a limited schedule. I think they run every half hour, and they might not be going to you Terminal until 1 of the last stops. I think the shuttle buses run in a circle. S9 check how much time you hace for you transfer, and be prepared the trip from a domestic terminal to the international terminal could take up to an hour or more.
If you are past security there should be a shuttle between terminals. Outside security, Airtrain.
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