You will likely need a resumé as part of the college process, or if you apply for a job or internship. It's also helpful to give this to the teacher(s) writing your recommendation. Below is an excellent model of a high school resumé (Scroll down!) Notice the FORMAT, the TENSE, and that everything is in reverse chronological order. You don't have to put the same exact items, but this is a good guide of format! Here are some other links...their formatting isn't as precise, but the content might be helpful.
Here are two of my resumés (a recent shortened one and my old one from a few years ago!) In case you'd like to see another format:
Here is a "how to" link with some advice, as well: http://jobsearch.about.com/od/sampleresume1/a/high-school-resume-examples.htm