Custom data series for iCloud Numbers graph

Hello,

First off, I'm enjoying using the Numbers application on iCloud so far. One thing that's bothering me though: I can't figure out how they made their graph in the Mortgage Calculator template only show three values? I've recreated the graph with five values, but I don't see where I can delete the second and fourth values to match their graph. I don't see anywhere in the Format panel to edit the data series once the graph has been created.

Hopefully this screen shot of the two graphs will help: