I know someone already posted something on this, but my computer wouldn't let me download his links...

So I can play scales pretty decently on guitar, and I've been playing trombone for like 7 years, so I know about theory and can always tell what key a song is in. BUt with guitar, since it's treble clef, I get so confused and I can never tell what key I'm playing in, although, I'm probably at the intermediate level with guitar. Can anyone help me out, please? Any help/suggestions would be greatly appreaciated. Thanks.
Well since you said its treble clef, I'm going to assume you are reading standard notation. In this case, its the same as bass clef in that 1 sharp is always G major, 2 sharps is always D major (or relative minor blah blah). Same with flats. I'm pretty sure this is correct, though I've heard people say the the key signature doesn't always tell you the key the song is in, which is somewhat odd.

This may not be what you are asking, if not, specify more please.
To see a World in a Grain of Sand
And a Heaven in a Wild Flower
Hold Infinity in the palm of your hand
And Eternity in an hour
Trombone and guitar are both C instruments. If a trombone song is in the key of Bb, it's in the key of Bb for guitar as well. There's no need for transposition.

Hey guys! I just started playing electric guitar should I get a Gabson Lay Pall or a Femdor Startokaster. I like the picks on the gabsons but i like how sweet femdors look. Beforre i get a gabson what company makes them?
But like I still don't get it... For guitar what key is a song with chords like G, Em, C, D in? I was told that those chords would be in the key of C, but that makes no sense