I created a chart in Microsoft excel and would now like to add instruction
boxes. For example, each column requires a different type of information to
be added. I would like to add some functionability to the chart in such a
way that when the column header is clicked, a box appears with the
instructions. I cannot remember how to do this and I can't find the answer
in the excel help. Any suggestions?

(I do not want to use the comment tool bar because I do not want to have
comments tied to a specific cell).

Thanks.