When applying for an internship it's important that you focus on your relevant experience and accomplishments to match the position description to show that your are best suited for the internship or job. The better you are able to match the needs of the employer, the more likely it will be that you will be called in to interview for the internship or the job.
A targeted resume highlights your education and experience. It is often recommended that college students keep their resume to one page unless their is extensive lab experience or written publications that you might want to highlight.
It's important to gear your resume (and cover letter) to include relevant experience like coursework, internships, jobs, or volunteer experiences that require the skills you need to successfully complete the internship or job.
If you are a first year or sophomore student without any relevant experience, you will want to include all of the experiences you have completed so far, whether they are relevant or not. High school experiences can be included as well as courses you have completed furing your first couple of years in college. The important thing is to be sure to get some relevant experience by doing internships while in college so that you will have a strong resume when you're ready to graduate.