Barre-Chords are what you need <img src="images/smiley_icons/icon_wink.gif" border=0 alt="Wink">
You put one of your fingers (usually the index) flat across several or all of the strings. So you can get 6 different notes on one fret with only one finger (amazing, he?). -> <a href="http://en.wikipedia.org/wiki/Barre_chord" target="_blank">http://en.wikipedia.org/wiki/Barre_chord</a>)
It takes some practise to get it right, but it's worth the effort.
For f# that will be: index flat across the 2nd fret; 4th fret: ring finger A-string, pinky D-String. The form of an e, only you move ist two frets up (one fret = one halftone).
Cheers
PepperDan