A cover letter is something that is attached to a CV or application form as a first impression of yourself.

 

Contact Information

Your contact information must be up to date in case the employer is trying to contact you. 

Your Contact Information
Your Name, address, area, post,code, phone number, city/town and your email address.

Employer Contact Information
Name, title, company, address, city, area and postal code

This information is the begin your cover letter, next it depends on the job you are applying for.  The little information you give will have to give a big impression for the employer. 

Next tell the employer why you are interested in this position.  This could be through hobbies,interests and/or experience. 

Here is a link to a basic structure of a cover letter.  COVER LETTER STRUCTURE

Here is a very basic template to get you started: