When you select a block of data on a spreadsheet and select Graphs of Block Data - Box Plot: Block Columns from the Graphs menu (or right-click on the selected block of data and select Graphs of Block Data - Box Plot: Block Columns from the resulting shortcut menu), a separate box plot of medians (and min/max values and 25th and 75th percentiles) is created for each of the columns in the block. Each box plot is displayed in a separate graph window.
If you want to include all plots in one graph window,
select Graphs of Block Data - Custom Graph from Block by Column from the Graphs menu,
click the More button on the Select Graph dialog,
and select the Single Window (Overlaid) option button.
To create a box plot of medians for each of the rows in the block, select Graphs of Block Data - Custom Graph from Block by Row from the Graphs menu.
Note that you can also create box plots for entire variables (columns) or cases (rows) by selecting Graphs of Block Data - Custom Graph for Entire Column or Graphs of Block Data - Custom Graph for Entire Row, respectively, from the Graphs menu. You can use these Custom Graphs to create a variety of types of box plots (e.g., Mean/SE/SD, Mean/SD/1.96*SD, and Mean/SE/1.96*SE).
For more information on box plots, see Graphs of Input Data - Box-Whisker by ... or 2D Box Plots.