Zapper app is for zapping events that have a zap-split set up - meaning first you have to create a zap-split event somehow, and then you can zap it with zapper.

Different apps create zap-split events for different purposes, but I haven't seen an app that allows you to manually build a zap-split - like choose event kind and choose zap receivers etc. I created the above zap-split manually from terminal, if you can do that try reading nip-57 - it's just "zap" tags with receiver pubkeys.