First, decide how many fades you want in your username (for example, a fade between 2 colors is a single fade. a fade between 3 is two fades).
Then, enter each part of your username you want to fade on separate lines.
Finally, click the first and second squares to choose the beginning and ending color for each fade.
You do not need to use all of the lines
You can Shift-click the color boxes to enter a hex color code.