Create the foundation of your song by laying down a few chords using a guitar, piano or synth. Common and simple chords for beginning song writers include G, C, D, and E minor.
Structure your song using your chords in different arrangements to create verses, chorus and bridges. Verses are parts of the song that have a similar melody but different lyrics. The chorus is basically the hook of your song: it has the same melody throughout the song with the same lyrics. Bridges are unique breaks away from the main melody lines of the verses and chorus.
Write lyrics for your song. Be flexible about changing your lyrics to fit the rhythm of your song.
Build a melody for your vocals on top of the chords you have arranged. Make a unique melody for verses, chorus and breaks so each part is different from the others.
Harmonize with the main vocal by having another person sing with you with a different melody line. Change the notes in the key of the chords you are using. Each chord is composed of three or more notes, so you can use these notes in different arrangements or add some that are in the same key as the chords.
Apply your lyrics to the melody and harmony. Doing so may take some editing to fit the rhythm of the music.