How to add multiple photos/videos/audios into a single entry in TimelineJS?

I want to add multiple photos/audios/videos into a single slide in TimelineJS, but I don’t know how? I downloaded the code from this github: https://github.com/NUKnightLab/TimelineJS3, and I am trying to change it in VScode to allow me to accomplish my goal, but I don’t know how to do it .

Will someone help me?

I don’t know how to do any of it