I need help with writing a story involving a boy and a harp?

In English we each had a picture igned and had to write a story about it with introduction, rising action, climax, resolution, theme, plot, all that good stuff. I'm completely stuck on story ideas. It shows a boy with a staff and a pointed-eared dog next to him in the woods. Across from them is a shiny harp. The title and caption is, "the harp." 'So it's true.' he thought. 'it's really true'. Please help!