Parse Server Http Requests

Hello, I’m trying to close an app with Http Request. I use the parse server as the backend.
My problem is that I don’t know how to make this connection. What is clear is that it somehow works via http.
You have to specify several keys. Then it stops with me and I don’t know how to continue.
Maybe someone has experience and could help me further.
I use Ionic 5 with Angular

LG Hoffle