Ok I got it. I just had to create the file and put the text in it. -.- :D
Ok so I got one last problem. When I configured my Xbox 360 Pad as a Retroarch Controller, it gave my dpad the followig config:
input_up_btn = "h0up" input_down_btn = "h0down" input_left_btn = "h0left" input_right_btn = "h0right"
Now I wonder how I should bring that in the gngeorc file.
I tried “J0Bh0up” and so on. But that didn’t work. :(