On the right side of your profile image (which can be found top middle) you will see a red star with your current level in it. This level is used to unlock tournaments and other items. For example, there are some spots that can only be unlocked after you have reached the required level.

You can increase your level by gaining reputation. You gain reputation by winning tournaments (higher placement gives more reputation) and getting status symbols in the Status Symbol menu (can be found at the bottom left). The red stars represent the amount of reputation points you can earn.

In your profile menu (which can be found top middle) you can see the progress you are making towards your next level displayed in reputation.

Good Luck and get on fire!