If you cant read the font
Its "<c7>Hi</c>
In the comment section the creator of the video put what number is what color example
The 4 in <c4> is blue
9 is dark red
It also works in clan chat you just say <c9>This text is in red text</c>
You know you did it right when you change your name because on screen it will show up in the color you want if it doesnt you did something wrong and you need to redo it
Also the "<" will be invisable when you type it in
I turned my name into blue