Dear Mr./Ms. ABC,

The opening paragraph should interest the reader. You should give the reason for your writing the letter. Give the information why you are interested in the company rather than saying that you are looking for a job.
The next paragraph should contain the details of your background. Tell the specific job in which you are interested.
Also give your qualifications in the next part. Tell your story but keep it short and to the point.
The last paragraph should include of you asking an appointment for the interview. You may also gives the dates on which you will be available to them for the further procedure.

Sincerely your’s,