Add record programmatically with values from two recordsources

My form uses three underlying tables: Classes, Students and a linking table
called StudentClassRegistrations, which stores the primary key for the
student and the class. I want to add a record to StudentClassRegistrations
based on the values selected in the form’s two combo boxes (The form’s
recordsource is set to Classes).

The first combo box allows the user to select a class (after which a subform
displays all students enrolled in that class.)

The second combo box allows the user to select the student to enroll.

I want to build an “Enroll Selected Student” command button that adds a
record to StudentClassesRegistrations, but have no idea how to accomplish
this via code. Any help will be enormously appreciated.

--
PJ Von
.