Update A Table When Changing Data In Another Table

I have a training Database in Access 2010 that I am creating. I have "courseindex" which is the table that has course titles and the course required frequency. I also have "trainingcompleted" which is the table that contains all training my employees have completed. The form "training" contains employee data and all training each employee has completed.

On the form "training", the training completed is selected from a combo box, which is pulled from the table "courseindex". When I update the combo box, I would like the training frequency field that corresponds to the selected training to auto fill in my "trainingcompleted" table.

Once completed I should be able to generate a report, where the user enters a date range and it will tell me who is due for training within that time frame. I have the forms, tables, and reports set up. I can enter the next due data in manually each time I update a record, but I would rather that data be updated automatically, since the frequency for each training will never change. I have over forty courses that employees must take. Some courses are required annually, some bi-annually, some every five years, etc...