There are 4 steps for that. The first is to complete the application.
What is the application name?
The application is called a Standard Permit , Driver License for Non - Driver ID Card PDF [ 2 ] MV-44.
What is the second step?
Determine what you need for identification at the DMV. You would need to complete this guide to know what you need for identification if you wan a REAL ID or an Enhanced ones.
Does my son need a new york state driver's license if he just comes here to study?
Is he going to be considered a resident of New York state or is he going to maintain an address of residence elsewhere?
He is not going to claim residency in the state.  His residency will remain in Canada between semesters and after completion of schooling.
Does he possess a Canadian drivers license that is current?