tying musical notes to frequencies

I need to sharpen a specific note (acoustic guitar) with some slight EQ--the string was a little dull and I want to punch it up just a little. The note is an F#. If I go to the parametric EQ effect dialog in my audio software (happens to be Sonar), I can enter a specific frequency to which I would like to apply gain. How do I know which frequency to use if it's an F# I'm interested in?

 

thanks, elambo, that actually did the trick for my dull note.

 

Well, dumb luck, I guess, but rolling off that frequency a tad really did improve the timbre of the offending note. Knowing the frequencies at least gets me in the ballpark....though obviously the ear is the real test, as I would wholeheartedly agree.