When you apply for a job, you need to send a cover letter along with your CV. A cover letter is a letter to the employer that says which position you're applying for and why you would be a good person for the job.
Why You Need a Cover Letter
Your cover letter introduces you to the employer and highlights the skills you have that are especially useful for the job you're applying for.
How to Write a Cover Letter
How to Send a Cover Letter
Always send a personal cover letter with your CV
Where to Get Help Writing a Cover Letter