You have a chance to apply for your absolute Dream Job. But, it requires you to write a Cover Letter, introducing yourself and WHY they should choose you. So, why SHOULD they choose you?  Write a formal letter (or you can consider it an informative essay) where you tell them why.   Consider the following:
- Skills you have that would help them 
- What makes you a good worker
- Academic achievements they should know about? (GPA's, AP classes, etc.)
- Other achievements? (Community Service, Volunteering at Church, etc.) 
- Any Work Experience that is relevant
- Any other info you think might help them see why you are right for the job.