There's buttons for all these when you go to compose a message.
Embedding Youtube videos:
Code: Select all
[youtube]http://www.youtube.com/watch?v=4nigRT2KmCE[/youtube]
Center align text:
Code: Select all
[center]Centered text[/center]
Centered text
Right align text:
Code: Select all
[right]Right aligned text[/right]
Right aligned text
Horizontal Rule:
Code: Select all
[hr][/hr]
Add in spoiler text (highlight with your cursor to expose):
Code: Select all
[spoiler]This text is hidden[/spoiler]
Embedded Flash:
Code: Select all
[flash=600,400]http://www.addictinggames.com/D78AQSAKQLQWI9/4383.swf[/flash]
As always, rules for content posted remain the same - don't post anything you wouldn't want your grandmother to see (all jokes about nasty grandmothers will be ignored).