Can anyone point me in the direction of an Access course on this site that explains how I would update my main form with a linked form?

For example, I have a data entry form (call it MAIN FORM) in my database that has a button to ADD NEW customers (rather than the user having to go out of this main form, into the new customer form and then back to this form after adding the new customer).  If I am adding a new customer from the main form, I want this form to automatically update with the new customer I just added upon closing the new customer form.  I've tried to link the customer data entry box to the new customer form and then refresh upon close of the customer form, but this is not working - I assume I am missing some steps...  Thanks!