Choose your topic. Hits have been written about everything from a girlfriend ("Peggy Sue") to politics ("Eve of Destruction") to love ("I Can't Help Falling in Love With You"). All of these songs can be played with three chords.
Determine your rhyme scheme. "Peggy Sue" is A, A, A, A.
Begin writing your lyric, paying attention to the meter of your lines. The lines need not be identical in meter, but they should usually be similar so the music will flow smoothly.
Write three to five verses for your song.
Write a chorus for your song.
Know that the "C" scale contains following notes and chords: C, D, E, F, G, A and B.
Remember that three-chord songs are almost always played using the root chord, in this case, C; the fourth chord, in this case F; and the major 7th of the fifth chord, here G7.
Play songs in the key of G by using the chords G, F and C7.
Learn songs in the key of E by playing the E, A and B7 chords. You should be able to sing in one of these keys because they are spaced throughout the scales.
Hum or sing your melody to make sure it fits your lyrics.
Sing the first phrase of your song while playing one of the three chords for the key of your song,
Try the root chord first. You may need to raise or lower your voice to fit the chord, or you may need to start in one of the other chords. Most songs start in the root chord. Practice is the only ways to improve your abilities in this area.
Continue playing the chord and sing the next phrase of your song. If the singing suddenly sounds out of tune, you probably need to play one of the other chords for that part.
Continue working out the chords for the rest of your song.