Not sure what you mean by "is the same name or something" but go to the design view of your subform and change the Default View property from Single Form (or Continuous Form) to DataSheet to view the subform as a table. I'm guessing that your relationship between the 2 tables is most likely a one-to-many where the ID type field in the main table matches a corresponding ID field in the name customers table. In the design view of your main form, if you select the subform and look at the properties, you'll see the Link Child Field and Link Master Field property where you select the matching ID field in both tables.
Expert Database Programming
MSAccess since 1.0, SQL Server since 6.5, Visual Basic (5.0, 6.0)