[HELP]Green pointy hills outside map

Hey, i have started working on a 2km map, i tried setting up cp and spawnpoints etc, i managed to get into the map, the problem is when i look outside the map i see big pointy green mountains all over, like needles sticking up, I cant see them in the editor, can i get rid of this somehow ? and is it possible to set somekind of background terrain on the sides of the map ?