Once the lobby is setup, the next thing to do is start creating arenas. Creating arenas are one of the easiest things to do in the SurvivalGames. Simply use worldedit to create a selection around the arena. Once you have the whole arena selected (Make sure you get to the top and bottom of the arena!) type /sg createarena. If all goes well you should be told that your arena was created.
After you have created the arena, use the command /sg setspawn next to set the next spawn point at the place were you are standing