Hi @Mirtemir ,
Do you want to trigger a flow by pressing a button in an app ?
Then you need to use the trigger named powerapps in your flow.
You need to create the flow like this:

Then you will create a flow with the trigger that you need.

Please notice that all the "ask in powerapps" that you select in the flow will be the parameters that you need to use in the formula to call the flow in powerapps.
Just like this:

After you create this flow successfully, you need to set your app like this:
choose the button that you want to trigger the flow, choose the flow that you want to trigger.

Then use formula like this to call this flow:
flowname.Run(paramaters)
//please fill in your flow name and the parameters that the flow needs
Best regards,