Find the current key of the song. You can do this by looking at the key signature. This is an area at the beginning of the staff lines that shows which notes are sharp (#) or flat (b). If you don't see any sharps or flats, the song is in the key of C/A minor. One sharp is the key of G/Em, two is D/Bm, three is A/F#m, four is E/C#m, five is B/G#m, six is F#/D#m and seven sharps is C#/A#m. If you see one flat, the key is F/Dm, two is Bb/Gm, three is Eb/Cm, four is Ab/Fm, five is Db/Bbm, six is Gb/Ebm and seven flats is Cb/Abm.
Determine the key to which you want to transpose a song. You may have to try several keys until one feels comfortable.
Count the half steps between the original key and the new key. The half steps in music are A, A#/Bb, B, C, C#/Db, D, D#/Eb, E, F, F#/Gb, G, G#/Ab. For instance, a song is written in the key of C, which may be too low for you to sing. Therefore, you might want to move it up to the key of E. E is four half steps up from C.
Transpose each note in the song from its original position to a note that is four half steps higher. If you are unsure about note placement, consult a note chart as a reference (see Resources).