1. Briefly introduce who you are, why you want to submit this position, what advantages you have, which is equivalent to a cover letter, and then attach your resume.
2. After your cover letter is written, write the main contents of your resume directly below, such as basic information, education, internship experience and so on. Attach a detailed resume.
Generally speaking, HR may face thousands of work emails every day, so I suggest you choose the second category, which can reduce the workload of HR and is not easy to be ignored. Don't simply write a sentence or two and take it away.
In addition, there are other things to pay attention to about resumes and cover letters. You can go to the website of Good Job Resume.
I hope I can help you and adopt it ~