With Instant 3d turned on, single-click on the Linear Pattern in the tree (or double-click if it's turned off). That will show the dimension and number of instances in the graphics area. They're probably stacked on top of each other, but you can click on one of them to move it. Then right-click on the number of instances and choose "Configure dimension" from the drop-down. That will take you to a simplified design table with a row for each configuration and a row where you can enter the desired number of instances for each. You can also create new configurations with this table.
One of the great things about Design Tables is utilizing the capabilities of Excel. Glenn describes one way to add a parameter to a DT. Another way is to just manually create one or more configurations and vary the parameters between the configurations. Then you can create a DT and it will automatically be loaded with these parameters. Once you have the fundamental values in your DT you can use the full set of Excel functions, including IF statements, to determine the values. It is far easier to do this type of logic in a DT/Excel than just using the equation capabilities in SWX. I've even created a DT with only one configuration and saved this as a parametric generic part for more easily seeing, commenting, and controlling the values. This worked great for the involute gear files I use, just open -> Save As Copy with a new name and then change to the new teeth, pitch, PA, etc.
When using Design Tables or Equations it is extremely helpful to FIRST change the generic name of the dimensions to something meaningful such as Pitch_Dia, Teeth, PressAngle, etc. If you do this before making the DT or using equations then these are the names that show up. Since this is my habit I haven't recently tried making the DT first and then changing the dimension name; this used to cause crashes and corrupted files.