PhantomLiege

Hi all, I've been playing DayZ for about a day now and I'm just starting to get the hang of it. I haven't come across a big town/city though like I see the most popular one is called "Elektro" and I would like to go there but I have no idea where to go. I've tried looking at my map ('M' key) but it's just all black, and I'm just looking for a way to see where I'm going. Does anyone know how? Or do I have to find an item/object around somewhere? Thanks.