Please help me to write an official letter to a corporation asking them to release an advertisement in our magazine.
I think you are asking how to write a business letter inviting a business corporation to advertise in a magazine for which you work.
Your letter should begin with identification of the name and mailing address of your company and the date on which the letter is being written. If you have the name of the specific person at the corporation who arranges advertising for the corporation, list his/her name and official title first, then the name and address of the corporation.
Use the person's name again in the salutation or greeting; if you don't have a name, begin the letter with "To Whom It May Concern." In the body of the letter, deliver your invitation for the corporation to advertise in your magazine. Give some reasons why this would be a good thing for the corporation - what are ways in which advertising in your magazine might help their business? In another paragraph, provide specific contact information about how to submit the ad, what the cost would be, any contact information you can provide, and a timeline regarding when the ad would be published after it is received and approved.
Close by thanking the corporation for its consideration of your magazine. Use "Respectfully" and your signature, followed by your printed name to end the letter. If you need to send any forms to be completed by the corporation, put "Enc." below your typed name to indicate there are enclosures with your letter.