The Histogram displays the distribution of values for a data set in bar graph format. The bin labels are displayed along the horizontal axis and the number of points in each division (or "bin") is displayed on the vertical axis.
Add a new histogram to your file by choosing Additional Graphs > Histogram from the Insert menu.
Double-click the FFT graph or choose Additional Graph Options > Histogram Options from the Options menu to access the Histogram Options dialog. In the dialog you can change which columns are displayed and other aspects of the graph's appearance.