BBCode (Bulletin Board Code) is a simple way for you to apply text-formatting or "smilies" to your profile, emails and blogs. Not all tags are available in all areas.
If BBCode can be used in any area, you will see a link to 'Supports BBCode' next to that area.
Simply click on the 'Supports BBCode' link and a pop up will appear showing examples that can be used.
If you want to make some text bold, here's an example:
[b]type your text here[/b]
So you would type [b] before the text you wish to show as bold and [/b] at the end of the text which should then return the text following that code back to normal.