How can I graph two sets of data on the same Excel graph?

Answer 1

You can create a secondary axis by selecting the data and right-clicking.  Select "Format Data Series" and then select Series Options (the 3 little columns).  Select Secondary Axis.  This is good if the additional data has much smaller, or much larger values.

Answer 2

I'm assuming you know how to graph one set of data in excel. 

When you finish creating the single-data set graph:

 

1. Right click anywhere in the plot area, (just not on the data points)

2.  Click "Select Data"

3.  Under "Legend Entries(Series)", click Add

4.  Delete what is in the "Series Values" box

5.  Grab the data you'd like to add as the second set

6.  Click "OK"

7.  Jump for joy!