In my opinion, the best way to write your essay is starting with a small introduction, including why you want to study arts. Thus, it would be good to include personal facts that lead you into this subject.
Describe your background starting from elementary, talk about your achievements (perhaps it is good to mention that you attend to arts museums, concerts, go to an art contest, etc). Also includes description of your high school process and your extracurricular/leisure time activities (painting, singing, playing an instrument...).
You may continue with your expectations about studying arts, try to persuade the reader how important it is that you study it. Finally, please mention your ideas/goals/thoughts about your future job and projects when you finish your studies.
Try to check your essay with someone that you consider who have good writing skills to help you organize the ideas.
Hope it helps.