You can upload audio files to the audio FX sound board that are in OGG or WAV format. Please check the Adafruit Audio FX guide for a full breakdown on supported sample rates and recommened settings.
Most DAW or video editing software come packaged with royalty free sound effects. In this project, I used a handful of electronic and firearm sounds from the Final Cut Pro X sound effects library. Layering them together to make an intricate sounding laser blast and mixing the audio levels to balance out the desired effect.
Adding audio the sound board is like adding files to a USB memory stick. Connect the fx board to your computer with a micro-USB cable. The fx board will load as "Adafruit" storage drive. There, you can drag-n-drop audio samples. Audio files must be named to a specific track in order to play properly. In this project, we connected the push button to pin #10 so our audio file name must contain T10. The trigger mode is also appended to the file name so the FX board knows what mode to play the sample.