How to configure a Selenium Server in Netbeans on a PHP project with my macbook?

I am a totaly «newbie» as for testing. My question is very specific and I couln'd found any answere on the internet. Because of that I am sorry if my question alrady been answered.

I have a PHP Netbeans-Project on my mac which I want to test with selenium-scenarios.
I want to configure the Selenium Server in Netbenas (you can see it here).
I have set the configs like this but I haven't any idea what I have to do with the last textbox. I also tried to start the stand-alone.jar with my terminal but for some reason the tests weren't still successful. Without the @javascript in the .feature file everything works fine but I need to test some javascript functions or buttons.
I found on the internet that I should select for the user exstension a path like /Applications/http://ift.tt/1f3ARxe but this folder doesn't exsisr and Netbeans needs a javascript file. I thought it perhaps means the firefox-driver.js so I downloaded and selected it but the server still doesn't start. I get not any error message or somethingelse ....

How I could start the selenium server?
How I have to configure my behat.yml for the selenium server correctly?
And how I have to configure my selenium server?

Thank you a lot for every kind of help!

PS: My macOS version is macOS High Sierra 10.13, I use the Netbeans dev version and I downloaded the selenium stable 3.6.0.jar.