Adding a secondary axis to an exisitng chart

[Randy]

When working through the Excel Help explanation, I can't find the "Series
Options" Where is it?

 

[Bernard Liengme]

Right click on one of the data series in the chart and from the shortcut
menu use Format Series;
Open the Axis tab and click on the Secondary Axis option
If the chart is column you will need some extra steps; see
http://peltiertech.com/Excel/Charts/ColumnsOnTwoAxes.html
best wishes