Sarah, you might want to learn how to count semitones so the next time you need to know where to put the capo you'll be able to calculate it yourself.

the notes go:

A
A#(Bb)
B
C
C#(Db)
D
D#(Eb)
E
F
F#(Gb)
G G#(Ab)
A... and so on in a circle.

The gap between each note and the next one on the list is called a semitone. Guitar frets correspond to semitones; if two notes are 5 semitones apart, then they will be 5 frets apart on a given string.

So let's say you know how to play a song in C, and someone asks you to play it in E:

C to C# to D to D# to E means that E is four semitones above C, so you can do this easily by sticking the capo on the fourth fret.

You can use the same principle of counting semitones to transpose a song without a capo - it's a question of adding the extra semitones to each chord in the original.

Suppose your song in G contains the chords G, C, D, Em, and Am. And suppose you decide to take Jon Freeman's advice of playing the D equivalent with the second fret capoed (which is probably the easiest route suggested here, unless you don't want to play the barre chord Bm).

Since D is 7 semitones above G, you just add 7 to every chord in your song:
G plus 7 becomes D
C plus 7 becomes G
D plus 7 becomes A
Em plus 7 becomes Bm
Am plus 7 becomes Em

Then since E is two semitones above D, your capo on the second fret will transpose your whole D song into E.

Note that major chords stay major, and minor chords stay minor.

And when counting semitones, note that usually there are 2 semitones (AKA one tone) between consective letter names, EXCEPT that there is only one semitone between B and C and between E and F. I know this seems odd, and there's probably some profound historical reason for it, but you should just accept this oddity. If you're familiar with the keyboard, you will remember that there is no black note between B and C, or E and F.

Good luck Sarah. I hope this info was neither over nor under your head, but if so, maybe it will be useful to somebody. I remember a time when I would only play songs that I found in G because C songs had Fs, and D songs had Bms, and A songs had F#ms, and I was afraid of barre chords... it was a totally liberating experience for me to discover that with a little math I could make those songs be in G, where none of the standard chords are barre chords.

I don't have a terror of barre chords anymore (now it's more of a healthy respect), so I don't do this as often anymore, but it's a nice tool to have.

Marion