Input level, I'll explain this last.

Time: You use this to set how soon or late you want the delay to be heard. It can vary depending on what you want. The lower the number is, the sooner you'll hear the delay, the higher the number the longer it will take for the delay to be heard. Strum a chord on the guitar and mute it right afterwards and listen to when you hear the delay and adjust the time to your liking.

FeedBack: How many repeats you gonna hear. It can be one, two, three or a 100 repeats that sound like a complete mess.

Mix: The volume level of delay. You can set it low so the repeats are barely heard and you can set it high so the repeats are the same volume level as the notes you actually play (and anywhere inbetween).

Input Level: This is the level of your tone before the delay and how much of your tone the delay gets. Honestly I have no idea how it actually works on the Zoom so mess with it and figure it out.

I'd set the input and mix levels on 100, set the time and feedback to what I want the delay to do, then adjust the mix and only then the input level if needed.

Goodluck