Cute picture, and I too applaud your decision to jump right in!
I took the liberty of doing a crop on your picture. Typically you want the subject looking into the wider space of the photo, i.e. in this case, your son on the right side, looking into the "empty" space. With him laid out on the wagon like that, that's a little hard to do. Also, my wife thought the rocks on the wall added a bit with the color.
Having said all that, I'll be the first to admit that I am NO expert--there are a lot--probably most--on here with more experience and better editing skills. I just thought I'd throw my two cents worth in with an example of a crop. I was going to play in Photoshop Elements and try to blur the background, but the previously mentioned wife decided I had better things to do.
Nice job. We look forward to seeing more from you!