example:

<b><size=18><color=#fff400>enter text</color></size></b></color></size></b>

18 - text size
#fff400 - text color

links:
symbols - http://www.fanpop.com/clubs/fanpop/articles/62472/title/how-spice-up-profile
color-palettes - https://www.color-hex.com/color-palettes/