You have 6 minutes to prepare before the wall falls, you cannot kill any players at this time. Basically, this is a preparation time for you to mine ores, materials, make defenses and/or plan your strategy with your teamates (Example: Which team are we going to target). 

After those 6 minutes of preperation time, the walls will fall and the fight begins. You can either rush other team's wither, defend yours, rush diamonds and/or fight other players. All of them can give you a certain amount of coins that can be used to upgrade stuff in the shop. When one of the wither dies, you can go to get final kills which refers to permanently kill people who have their wither dead.

When all of the withers are dead, deathmatch begins, you will start taking hunger if you are in a base. The only way that you can avoid hunger is to going to the middle.

When there is only one team standing, that team will become the winner. You will recieve the win even if you are dead.