What to wear with rolled up khaki pants and brown ankle boots?

The khaki pants are a green colour, and they finish about an inch under my knee. The boots are brown and are ankle length with some braiding around the sides for decoration. I wear the pants with a large white belt as they are a lttile big, and I was wondering what would go well with them shirt wise? I'm only 13, and i'm thinking more casual attire than formal :)