Help me make a online server

Hello minecraft players.My friend really wants to make a online minecraft server but he doesn't know how to and he's really bumbed so that is why i made this topic.So please tell me how to make a online mincraft server so you can see my friends work.(if you know how to make a online minecraft server please tell me by commenting on this topic and if you are the first one to tell me how to I will create you a skin of your choice and i will do my 100 percent best).