How to swap discs for Playstation Games.

Hello, I recently helped a friend emulate Final Fantasy 7, which is a game with multiple discs. I told her to download Duckstation, I'm not too familiar with Playstation emulation though. Nor am I familiar with how the multiple discs work, but there was an option for swapping discs on Duckstation. I think she should be able to figure it out but I'm just asking in case. Any help is appreciated!