Using a doorframe (I think) to hide stormglass frane

A friend showed me how to place a frame, then put stormglass windows and from the outside you couldn’t see the SG frame, just tge glass. I don’t remember how to make it work. Can anyone give me tge step by step?

Place a foundation, even or flush-ish on the ground. Place four walls on each side of the foundation. Place a foundation in the middle, inside of your four walls. Upgrade your walls to either window frame wall pieces, or upgrade walls to doorframes.