All events in your life serve a purpose and they want to know what purpose graduation had for you. You can approach this chronologically, and your essay will discuss what you have accomplished and learned (past), examples of how you learned it and what your goals are now (present), and end with the importance of what you have learned and how graduating from college (future) will allow you that same feeling of importance and accomplishment.
Always start with brainstorming (PLAN) about what is important to you about your education, how that relates to certain goals, and the personal strength and sense of accomplishment you may have learned in the process. ORGANIZE your ideas into the standard 5 paragraph response: Intro--what you will discuss/prove; 3 supporting paragraphs (each a developed example of your proof); and a conclusion--what you have shown and proved. WRITE a draft. EDIT and get others to proofread, then REWRITE. Keep going until you are satisfied that you have done your best!
You need to begin by thinking about the topic. Why was graduation important to you? I assume since we are speaking in past tense and given you are a college freshman, we are focusing on your high school graduation. What was the big deal for you? Make a list of all the things that made that day a memorable one for you. From that list, choose three or four things that are most important to use in your paper. You mentioned comparing and contrasting you and a character, but not which character. I have included a link for writing a comparison and contrast essay.
You will want to get something to get the reader's attention. You could you a quote, a fact, blunt statement, a question, or a story to begin.
What is something that sticks out to you about graduation? whether is was good or bad, what was memorable? was there a thought you had throughout the day? have you learned something as you have compared who you are now compared to who you thought you were at graduation or in high school in general?
use a quote, fact, blunt statement, question, or story to get the reader into the visual of graduation, explain the situation or thoughts, and then go into your thesis statement at the end of the intro paragraph (or page(s) depending on how long the essay needs to be.
Good luck!! Enjoy!!