A effective artist statement tells the viewer some information that helps them to appreciate your artwork. Sometimes that information is about the process that went into making the photograph. Sometimes it is about the effect you are trying to achieve. Or perhaps you wanted to make a statement about the subject of your photograph, such as a commentary on the environment, for example. Use the Artist Statement to tell your story about the making of the artwork.
Things to consider:
Be yourself. Explain your ideas in your own words.
Did you have to make some interesting choices to make your photograph? If so, explain these. For example, did you climb a tree to get a unique perspective? Did you purposefully get up early to take advantage of the morning light?
What were you trying to achieve in your photograph? A specific feeling? A specific idea?
What does your art mean to you? Why are you submitting this particular photograph?