Yeah, there aren't any instructions. Most of us discovered it by using what works in the in-game text chat.
[3333FF]The colored text goes here[-]
The first brackets contain the hex color you want the font to be, and to end it use [-].
Not sure on using a different font offhand though. Just colors. There is also a finite limit to the amount of data that you can put in the description section which is extremely annoying given how large the space is.