Instructions
Find an instrumental track to serve as the background for your first song. While many rappers produce their own beats, producing is a completely different skillset than rapping and you will need to learn it separately. Many bands release songs that are only instrumental, and a variety of sample rap beats are available on the web.
Decide on an approach for your song. Artists often rap about their aspirations, their personal struggles, or their run-ins with the law. What you rap about depends entirely on your personal experience.
Write the first verse out on a piece of paper or in a word processor. Say the words along to the music to make sure they fit, and try to rhyme the end of every line. There are as many ways to rhyme as there are to rap, so feel free to do whatever feels most natural. Rap is about artistic expression.
Develop the chorus, or hook to your song This part repeats later and is the part you want your listeners to sing. It should reinforce the main themes of your song without being too distracting or repetitive.
Add another couple of verses, throwing the chorus in between them. With that done, you should now have a full-length amateur rap song.
Practice rapping your song until you have it memorized, and then prepare to record the track or show it off to friends. When the song is comfortably in mind, you will be able to improvise on inflections or add new lines as you go.