Doug,
If the RecordSource of your form is a table (bad idea), add the new field
to the table.
If the RecordSource of your form is a query (good idea), get the query in
Design view and add the new field to the query.
Then get the form in Design View, add a new textbox, select its properties
by right-clicking, and set it's ControlSource (use the pulldown list) to the
new field.
That's it!
Wayne