While there's no right way or wrong way to format your cover letter, the style below has produced results for my clients since 1995. You may wish to modify this format to match the fonts or style used in your résumé.
Your Name
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111 S. 3rd St., Apt. #101
Your town, MN 55082
123-456-7890
emailaddress@aol.com
EMPLOYER'S NAME
ADDRESS
ADDRESS
DATE
Dear Employer (INSERT NAME, IF KNOWN):
INSERT COVER LETTER BODY
Sincerely,
Your name
Enclosure: résumé