You can add curves and other drawing objects only to a chart. You cannot add them to the datasheet.
On the Drawing toolbar, click AutoShapes, point to Lines, and then click Curve .
Click where you want the shape to start, and then continue to move the mouse and click wherever you want to add a curve.
To end the shape and leave it open, double-click it at any point.
To close the shape, click near its starting point.
Tip After you complete a curve, you can close an open shape or open a closed one. Right-click the curve, and then click Close Curve or Open Curve on the shortcut menu.