Some of the greatest songwriters in the world can't read or write music. Smokey Robinson can't read of write music, but he wrote some of most beautifull songs you will ever hear. Barry White use to write songs for an orchestra and he couldn't read or write music. So did Curtis Mayfield. If you can communicate your ideas to others, than you can write songs. Thats all it really is. Just communication. How you do it doesn't matter. Sure writing music makes it easier but that doesn't mean its a good song. And thats the key as long as its a good song, people will want to hear it, sing it and buy it. So if you can hum or sing a Melody and put lyrics to it, you can write a song. Next, get you a musician who can hear what you are trying to say and can write it down or record it so you can demo it to others who might want to sing or record it. Don't forget to send in a copy to the copywrite office.