Vivarium Backround

[Hsu Twins]

Hey guys, I recently decided to make a background for my 20 gallon vivarium. I want to use the expandable foam on a thin foam board. I also want to add pots so i can out plants in. Can anyone tell me how to do this and what supplies to get, i've already looked at a lot of videos on youtube but still dont really get how, i don't want to mess this up.

Thanks,
Erik