For all of the elements you have to choose a trigger that activates your ability to use your power. This trigger could be anything from a specific hand gesture to a complicated series of blinks- this might not be the best choice, it's just and example. It doesn't matter as long as it's there. You will choose this trigger in the sponsorship task and continue to use it throughout the games. 

Pushing past the limited amount of time you have to use your powers before your energy runs out will lead to unconsciousness.

Fire:

If you are a Fire Elemental then you can manipulate fire. It won't hurt you, but it will hurt others. You can create a fire but you cannot use your powers nonstop for longer than a half an hour. You can shape the fire as well, but complicated shapes drain you two times faster and overextending yourself will lead to unconsciousness.

Water:

Being a Water Elemental, among other things, enables you to breathe under water. You can also manipulate water and move it, but the water can only move so far from its source. You can sense shifts in the water and use it to your advantage in a fight. You can breathe under water indefinitely and you don't need a trigger for it, but you do need a trigger (a word, an action, a certain hand movement, whatever you choose) if you want to do anything else with the water. You'll run out of energy to work with after a half an hour of constantly working with the water, same as any other element. Also, you can control solid water or water vapor, but it takes two times more energy to do it. You can also control water that is inside of other substances, but you cannot control the entire substance.

Earth:

If you are an Earth Elemental then you can move the earth, but moving it in large amounts is impossible. You can raise or lower the earth in small amounts to create walls or holes (maybe about five feet long and two feet thick at most, five feet in diameter if you're making a hole and six feet deep) and you can also create mini earth quakes (those would cover maybe several hundred yards before dissipating.) You could also move dirt into the air to create a hole and then fill it in again, which could be useful at times.

Air:

Manipulating air can allow you to jump higher or even fly, depending on your ability to control your powers, however, flying takes a lot out of you and you can only maintain flight for about ten minutes before collapse. You can also create mini windstorms and air funnels.