sorry but i don't know too much english and i don't understand exactly what i have to do , could you say me in simple word what my friend need?
PS: and he canot play singleplayer (sorry for the english , I learn it thanks to the videogames)
If single player doesn't work then multiplayer won't work either. But maybe I misunderstand you. If single player is not working then what is the error?
Are you trying to run your own server or are you trying to connect to the public server?
If you are trying to run your own server then you need to make sure that the ports are mapped properly on your router.
If you are trying to connect to my server (the one that displays by default when you try to do a multiplayer game) then there must be some other problem. I see people connecting all day so I know my end works.
If you can then please explain what you have tried already.