Instructions
Start Steam and type your email and password to login to your account.
Click "Friends" and select the option to "Change Profile Name."
Type your desired username but add "^#" before each letter to change its color. If you want to change your name to red and your username is johndoe, for example, you would type "^1johndoe". The available options are ^1 for red, ^2 for green, ^3 for yellow, ^4 for blue, ^5 for cyan, ^6 for purple, ^7 for white, ^8 for gray and ^9 for a random color.