Well you can do it two ways really, but the best way would be going onto reply (The small box on the righ hand side, has the reply option there). If you go onto there across the top it has mant options that includes: smileys, font, color, size, bolt, underling etc. If you clikf on color you can usually chose and it will appear like this after chosing your color on the drop box '[ color=pink ][ /color ]' the font you just click on and usually comes up a font, but you can change it '[ font=wester ][/font ]' is the one I usually change mine to.
(But without the spaces between the ['s).
Hope this helped
~Taylor. [\font]