In the sentence, the first blank requires the preposition 'to' because it indicates the recipient of the letter that John McCord wrote. The verb 'wrote' is typically followed by 'to' when specifying who the letter is addressed to. The second blank requires the word 'stating,' which is the present participle form of the verb 'state.' This form is used to describe the action of expressing or declaring something, which in this case refers to the content of the letter that John McCord is writing.