First of all, briefly introduce yourself, including name, age, college and major, personal hobbies and the position you want to apply for.
Secondly, introduce what you have learned in the professional field of HR, the courses you have studied and the social practices you have participated in.
Third, talk about your views on the HR job, what do you think this position should do or play, and what capabilities it should have.
Finally, talk about your confidence and determination to apply for this position.
These four points are necessary for writing a cover letter in English or Chinese.
My humble opinion, I hope it will help you.