Through your cover letter, you aim to convey to the hiring manager:
1. Who you are & why you want the job.
2. Your relevant skills/ past experiences and how they pertain to this job. Connect your experiences with the responsibilities outlined in the job description to show that you understand what will be required.
3. The conclusion. reiterate the main ‘benefit’ of hiring you, thank them, and let them know how you will follow-up.