Use the mouse to rearrange the blue data points. Move the 2 red dots to create your [b][color=#ff0000]line of best fit[/color][/b]. The [b]residuals[/b] checkbox shows the corresponding residuals relative to the red line. The [color=#6aa84f][b]Linear Regression[/b][/color] checkbox shows the "best fit" line to the data. If you move the red line to coincide with the Linear Regression you will see the "Best Fit" residuals.