To begin a business letter, you should start by including your contact information, the date, and the recipient's contact information. Here is a format you can follow:
Your Name
Your Position or Title (optional)
Your Company (optional)
Your Address
Your City, State, Zip Code
Your Phone Number
Your Email Address
Date
Recipient's Name
Recipient's Position or Title (optional)
Recipient's Company
Recipient's Address
Recipient's City, State, Zip Code
Salutation (e.g. Dear Mr./Ms./Dr. Last Name,)
From there, you can move on to the body of the letter, which should include your message or request. It's important to keep your tone professional and courteous, and to be clear and concise in your writing.