How to: Add Text Annotations to Diagrams (Visual Database Tools)
To make notes or comments on a diagram you can add text annotations.
To add text annotations to diagrams
Open the diagram to which you want to add an annotation.
Right-click in the empty space of the Diagram window.
From the shortcut menu click New Text Annotation.
Type your note into the text field that appears.
Note
To change the font, right click the text field and click Set Text Annotation Font.