Pick the main subject of the song. When you're ready to write a song, use the skills you've been developing by practicing every day. This time, instead of an object in the room, pick that which the song is about. It might be a girl, it might be a car. It could be an abstract concept like love, or a situation like riding on a train. Now, instead of cramming that into four rhyming lines, write a story about it, and use all your senses to describe the story.
It doesn't have to be well written, or even grammatically correct. Think of it more like a stream of consciousness "thought poem," and write what comes to mind.
When you're done, examine your writing. What parts strike a particularly strong emotional chord within you? What parts are expository, and what parts bear repeating?