Use the first paragraph to thank the interviewer for taking the time to meet with you. Mention your interest in the job and how enthusiastic you are about it.
The second paragraph of your thank you letter should include the reasons why you are an excellent candidate for the job. List specific skills that relate to the job you interviewed for. The more detailed you are, the more the interviewer will know about your qualifications.
The third paragraph (optional) can be used to mention anything that you didn#t bring up at the interview that you#d like the employer to know. This gives you another chance to make a good impression, especially if you remembered something you should have said after the interview.
In your closing paragraph, reiterate your appreciation for being considered for the the job and let the interviewer know you are looking forward to hearing from him or her soon.