Http Requests with Ionic 5 Angular

Hello, I’m trying to close an app with Http Request. For the front end, I use Ionic 5 with Angular.
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.
The principle does not really matter whether with Angular or additionally Ionic.

LG Hoffle

You can either user the Parse JS SDK or do a Http Request directly to the REST API.