To begin have your name, address including city and state along with contact info at the top sort of in a listed format to the left of the page. Then include the date that you are writing the letter. After that put the address of the company, using the same format as your address, you can address it to Human Resources. Then include a salutation "Dear Hiring Committee:" or "Dear Hiring Manager:"
In the first paragraph, explain your purpose for writing the letter..."to express my interest in the position of......" Then include the job title and position number. After that sentence, inform of where you found the job. Finally, discuss, in one sentence, what attracted you to it and what you can offer...."I can use my skills, education, and experience in this position."
In the second paragraph, detail your skills, experiences and education that you can use in the position based on the job description (heavily use the job description to help in writing the letter). Assure them that you understand what they're asking for then be honest and clear with what you've done that's similar.
To end the letter, third paragraph, thank them for their time and consideration. Then welcome the opportunity to further discuss your qualifications and interest. Close with offer for them to contact you with any questions. (You can switch order of sentences in last paragraph.
Your first and last name typed