You should focus on your strengths. What are some of your accomplishments that you are especially proud of? What are your personal characteristics that will make you a good candidate? (Things like: "I work well with people" "I have a good command on language" "I'm a hard worker" "I'm very efficient at writing computer code" "I'm particularly good at listening, understanding, and following through"). BUT . . . it's also good to show that you are a well-rounded person. So briefly tell them about sports activities, hobbies, groups that you are active in.