This project was a GREAT exercise because I don't consider myself a beginner, but I fumbled a lot, and learned more as a result. I made the green layer first and used water color brushes for the gradients. It put it all in a group folder. I duped that group as peach and transformed as smaller, and modified some individual shapes. Then I duped a folder again to make pink underneath to give it a feeling of depth. That layer has the adjustment layers, as you can see in the layers screenshot.
You may think "piece of cake" rather than soup, but try it, and you'll see how the simplicity of the project can create a complex piece.