From The Document Foundation Wiki
How can I add a field to a form?
Adding a field to a table
- Open the database
- In the left hand column, click on the "Tables" icon.
- Right click on the name of the table to change and select "Edit" in the context menu.
- Insert a field by a right click at the left end of the required line and select "Insert Rows" on the context menu.
- In the form toolbar, click on "View", then "Toolbars", and select "Form design"
- In the design toolbar, click on the icon to add a field
This opens the add field dialogue.
- Click on a form control: the table field list appears in a window.
- Click on a field and hold the button down, drag the field onto the form.
- Access the new control with the form navigator.
- The control properties (the name appearing correctly) confirms that the control is properly connected to the field that was added to the table.