After you open the form to which you want to add a field in Design view, click the Field List button on the Standard toolbar in the main Access window.
A list of fields in the current table appears. Click the field you want to add to select it.
Drag the field to the location on the form where you want it to be placed.
Access adds a label and text box for the new field. (You may have to make some adjustments to the field's size and placement.) Click the Save button to save the form design.