A business letter consists mainly of the following among many other features:
At the top is contact Information of the sender and receiver, usually a physical address or an email address, or both. This is closely followed by the salutation. It pays to know the gender or name of the addressee. Then we have the body of the letter that is preceded by a reference that introduces the receiver to what the mail is about.
The body of the business letter details explicitly with the simplest of words what the addresser wants to communicate. You should always remember to leave a space between paragraphs. No ambiguities or sweet words are used in business letters. The final line should recap your reason for writing and thank the reader for assessing your request. The letter should be single spaced and justified to the left.
The close should sound approving and should be followed by a hand written signature if the letter is to be mailed, or a typed signature.