Select page 7, or planter page.
Select page 3 within the planter VT.
On this page you will find most of your downforce contols. You can adjust your downforce with the upper left box. The graphs on the bottom can be cycled through to allow you to look at different metrics on the graphs.
Lastly, many of these same graphs and widgets can be added to normal run pages as well. See the Run page configuration in general if you are unsure how to edit these pages.