How to define parameters inside view?

Hello everyone,

I am nearly finished with my example project but having difficulties setting parameters. 

What I have:

• Direct Query to Stored Procedure with parameters
• Costum visualisation that uses the parameters. 
• Gateway, database server and reporting server running on same computer under same username. 
• A working webpage running on App.PowerBI and a working webpage running locally with the reporting server. 

What I dont have:

• A way to set the parameters inside the webpage
• Something like SSRS: 

• Or a popup like Power BI Desktop:

It seems like an arbitrary simple feature, am I just not looking at the right place?