While you're on the garage, tap on your username. This will take you to your profile page.

On the top right section of the screen you will be able to find a pencil icon with the option "Edit". By tapping this icon a small pop-up will appear that allows you to type in a new name of your choice. After typing a new name, select “Ok” and that's it!

Furthermore, it is important to remember that the first name change is free, but for future changes, you'll have to pay a small fee. So double check the spelling and make sure to choose a nickname you like!