I'm having trouble getting two labels on the X axis. My data is such
that there is a subject's name and then two different situations for
that subject, each with a pre- and post-score. So, for each subject,
there are 4 histogram bars in 2 groups of 2.

I am trying to figure out how to have my category axis labels with the
subject's name which would go below a number 1 and a number 2. Excel
will only let me have one category value (the 1 and 2), and I cannot
figure out how to add the subject's name below those values.

Any assistance would be much appreciated! Thanks!

Sample data:

John
behavior 1
pre: 5
post: 10

John
behavior 2
pre: 6
post: 8

I'd like the X axis to read "JOHN" with a 1 under the first 2 bars and
a 2 under the second 2 bars.