You can create text labels to mark important points on a chart.
NOTE: To create a text label in the Chart window, you must display the Chart toolbar. To display the Chart toolbar, right-click the Chart window and select Show Toolbar from the Chart window pop-up menu. Click here for more information.
Perform the following to create a text label on a chart:
From the Chart
toolbar, click 
NOTE: If you do not see this button, you need to display
the Chart toolbar.
Click the mouse cursor over the position you want the place the label. A new blank text label appears.
Type label text into the field
Press Enter to save the text into the label.