Making button start external .exe file HELP!!!!

Soo…I dont want to open exe file inside game window, i want to make window from external file…
And even if like i make something like this(For url because THERE IS NOTHING FOR OPENING FILES);

  using UnityEngine;
    using System.Collections;
    
    public class OpenInBrowser : MonoBehaviour {	
    
    	void FFA() {
         Application.OpenURL("www.agar.io/?ip=192.168.0.1:911");	
    	}

    
    	void FFAFF() {
         Application.OpenURL("www.agar.io/?ip=192.168.0.1:912");	
    	}
    }

when i make button in unity, and than go to inspector, i cannot add FFAFF(yea i made empty object…)

What can i do? PLEASE answer

Here like nobody answers :frowning: