enroll in — to officially register yourself or someone else as a member of an institution, course, or program

a young student sits across from a friendly admissions officer at a wooden desk, carefully filling out application forms with a pen. The officer points to specific sections on the paperwork while explaining the registration process. After completing the forms, the student hands the documents back to the officer who stamps them with an official seal. The officer then places the approved paperwork into a folder marked with the university colors. Other students wait in line behind them, holding their own application materials. someone officially registering themselves as a member of an institution or program