A letter

Dear Lidia Cojocaru: In America it is customary to write Dear Lidia, if it is a friend you know well and Dear Ms. Cojocaru, if the letter is a business letter. Ms. includes both Miss and Mrs and is used for both married and unmarried women so is the most modern and polite way to adress a woman in 2014. When writing a letter usually your greeting is followed by a comma "," and not a colon ":". 

I apologize for have not been able to answer before. This is correct English but what I would have written is: I apologize for not having been able to answer you earlier. I don´t have the pleasure of meeting your publishing house but I´m interested. I'm not exactly sure what you meant here. Do you mean: I won't have the pleasure of meeting you at your publishing house, but I am none-the-less interested in receiving more information about your services????  I will be glad on receiving more information about your services I would be delighted to or happy to receive more information on your services. I will be glad to receive more information is also correct, but not as often used. 

Sincerely.

Sincerely, 

So much about such a short note, but writing a business letter is something Americans study in school to get right! It's not easy.

Good job. 

Dear Lidia Cojocaru:

I apologise for not answering earlier. I have not had the pleasure of meeting you at your publishing house yet but I am interested in it. I would be happy to receive more information of your services.
I look forward to hearing from you soon

Yours sincerely.