First you have to be an Elite Member (it's free) and you have to be a clan leader. Which means that you have to establish a clan on Elite. If you have both of those things covered, then all you have to do is go into Elite, select competitions and enlist in the competitions available. Each one has specific goals and start/end times. If you click on the competition those details will pop up. Complete the objective of the competition during the event time and you will earn xp for your clan. Clan xp allows your clan to level up. Reaching a lvl 10 clan will allow you to have a gold clan tag.