Your Name
Your Address
Your City, State, Zip Code
Your Phone Number
Your Email

Date

Name
Job Title
Company
Street
City, State Zip

Dear Mr./Ms. Last Name,

(Keep all of the body text short and to the point)
-State how you heard about the opening and express your interest in the job.

-Express why you are interested in the position (i.e. I am interested in this career and state reasons why)

-State why you feel you would be an asset to the company.

-Briefly list any schooling or degrees attained, special interests that make you stand out, and any special clubs, honors, or awards that highlight your own personal success. (Don't be too wordy or you will loose the interest of the reader. The resume is where you can list everything.

-Open the door and invite an interview (ie. I look forward to discussing the position with you at a convenient time. I can be reached at 800-555-1212)

-Thank them for their time and consideration and reiterate that you look forward to speaking with them

Sincerely,

(Your Signature goes here so leave a few lines open)

Your Typed Name
References :
personal experience
Google is GREAT resource for job related writing

Your query requires a detailed answer. You can check out http://www.positionadvice.info for some useful info and tips. Good luck!
References :