Form fields - multiple and conditional choice

[Hank_]

I want to build a PowerApp for reporting Issues:

In this App you should be able to report basic issues. You can add a description to the report and multiple categories.

• Categories are organized in lower and higher categories like this:
• 

So: Depending on the higher_categorie choice I should be given the related lower_categorie choices

Questions: How do I do I get these multiple choices and dependency choices? I'm quiet stuck here. 

Disclamer: I'm new to PowerApps and programing in general. Thanks 🙂