How to replace refrigerator paneling with stainless?
Typically wood panels are installed as part of the cabinetry, the fridge panel is installed at the same time as the kitchen cabinets.

There is a removable edge at the door that is used to install and remove the panel. Once that is removed the panel slides out from one side. The replacement SS panel will go in the same groove that held the wood panel. The edge of the wood panel that went into the groove is usually 1/4" thick, so to add a metal panel in its place a backer of corrugated cardboard needs to be added in the back of the SS panel to keep it from moving excessively.