Hard to believe this is your first painting, you could teach me some good ideas.
Actually a very good painting for a first attempt, seems far above the average for a first try.
I was going to make a comment on the first image here yet it was corrected in the second image you posted after making some changes.
Looking at the second image the only thing I would change is the grass background behind the boys head top hair area. Break it up a little so that it does not seem to flow parallel to the head following its' shape, or extend the green over all the black area that extends to the top right corner. This could actually be how the photo looks yet would be a way of people viewing your painting not interpreting the grass background as being something associated with the boys' head. When creating artwork you have to realize that photo realism is not the only type of expression. As a way of preventing someone from believing there is some form of abstract or surrealistic expression in your composition you might want to avoid anything in the composition that could lead to that impression.