How do i send a tweet to a topic and not a user?

[Lord Zane Vorhis]

example: http://twitter.com/#search?q=Goodnight how would I send a tweet to that? Would I just do @Goodnight or is there a different method for general topics?

[Ben]

They aren't doing anything special - Twitter just looks for the word you searched for in others' tweets. Trended topics are just non-article words that appear a lot in current tweets. You can make sure it shows up with a hash tag (#).