How to assign power supply nets to planes ?

Hello all,

there are two plane layers in my design. In Xpedition xPCB Layout, I have connected them to GND and 3.3v power supply nets. When I open "Edit Power- Supply Nets " window, it does not show me the planes. My question is how can I assign GND and 3.3v nets to the planes ?. I will attach an image which shows my stackup and Edit Power- Supply Nets  window. Do I really need to assign power supply nets to planes or is it assigned automatically ?

Thank you.