There are several things to consider when writing a cover letter. I will assume this is a cover letter for a job. At the top of the page, in the center, you should list your name, address, city, state, and zip code, and some contact information. The next step is to write out the date.
Then you begin the body of the cover letter. Be sure to start with a greeting. You should then indicate that you are applying for a specific job. Be very clear about which job you are applying for. You should indicate what materials are being sent or where those materials can be accessed. It might be helpful to indicate the name of a person who may have steered you to the job. Make sure you show you are passionate and excited in the opening.
Here is a sample cover letter. It could look like this:
1111 Willow Way
My City, CA 91609
October 24, 2016
Dear Ms. Smith,
I am applying for the seventh and eighth grade Social Studies position at Happy Hollow School. I have been teaching Social Studies for the past five years, and I have always been hoping to teach at your school. I am very passionate about this subject. I have developed many lesson plans that have been published. I also am active in state and national Social Studies organizations. Jim Dooling, one of your Science teachers, recommended that I apply for this job. I look forward to discussing this position with you in person. I have enclosed my resume and two sample lessons that I have published. I am very excited about this opportunity!