Need more information.
In general, create your chart using a chart type that represents some of the
series in your ultimate chart. One by one as needed, select a series, and
change its chart type (right click and choose Chart Type or Change Chart
Type). Then one by one as needed, select a series and assign it to the
secondary axis (right click, Format Series, Axis tab or in 2007 the first
tab you see).
- Jon