Step 1: Building the Perimeter
First of, this is a general guide, not something that is step by step. First make a complete square on the ground or floating in the air. It doesn't matter which, just make sure that it is a perfect square.
Step 2: Building the Dividing Walls
Put up walls between each building area. You can either have a two team arena or a four team arena. Mine was four team.
Step 3: Decorate Each Team Area
Make sure they all look identical, except if you want a unique color for each team like me.
Step 4: Cover the Whole Thing With Any Block
Glass looks cool
Step 5: Make a Cool Entrance
Mine requires you to walk into a little room out side the arena, walk down a ladder Ito a small hallway then climb up into the arena.