I need help about make the text blank out?

[Lord_DarthRevan]

I need help.
I don't understand how to type a spoilar and make it blank out so you have to hylight it to see what it says.

[SIZE=3]Happy New Year[SIZE=3]

[FiEND_138]

http://www.lucasforums.com/announcement.php?s=&forumid=523

[Lord_DarthRevan]

thanx