I read with interest your advertisement in the New York Times of September 12, 1999 for the post of Administrative Assistant in the Archives Section of the National Library, and would like to apply for this position.
In the second paragraph you should concisely elaborate on those aspects of your experience or qualifications which are related to this company's needs. If you have a lot of material, this can be extended to twqo paragraphs. If you are replying to an advertisement, make sure you read carefully the requirements for the position and that you have mentioned briefly how your experience meets each of them. (If you cannot meet one of the requirements, don't apologize or emphasize your shortcomings: either suggest what alternative experience or qualifications you might be able to offer instead, or if you have none, just don't mention that point). The ideal structure in this part of the letter is to mention the relevant experience, then say what skills you have gained from this experience that are relevant to this job. It is also very good here to describe special achievements which show you to be an independent, creative and dynamic person.
My experience in working with a team of four colleagues at the University of Riga has enabled me to develop the skills of collaboration, negotiation and co-operative problem solving. While in this position I also designed and put into operation a unique database system for the storage of data about archaeological sites.
The next (penultimate) paragraph should normally indicate how this particular job or company would fit into your own career plans. A company is much more likely to employ someone they think will enjoy working for them than someone who will leave at the first opportunity. Some guides to writing suggest you should insert a proactive statement here to show you are assertive and professionally persistent. It would perhaps be preferable to say that your whole letter should give the overall impression of professionalism and persistence.
A job at the National Library is particularly appealing to me as it would give me the chance expand my interest and experience in archaeological research. I feel sure that the Library would also prove a stimulating work environment that would enable me to offer my best.
In the final section of the letter, include a sentence to the effect that you are happy to provide further information and that you hope to hear from the company regarding the possibility of an interview.