Assuming you actually want to do something and not display a message box each time, there are a number of ways to do it.
If you want to update values in one or more columns in an associated table you could create an update query (or even more than one update query). There are a lot of things you can do in queries, even some fairly complex things, so that's probably the best way to go.
If you want to perform a lot of operations for each customer, then you probably need to create a recordset of the customers and loop through the recordset so you get all of the customer numbers. For each customer execute all the code you want.
Bob