Hi again, sharifa!
I'm sure that you know more about your business than anyone else here.
As far as an introduction letter is concerned, my suggestion would be for you to start a draft of such a letter on this thread, without putting any contact information in it. If you do that, I'm sure that there will be those of us who'll be willing to come along and make suggestions as to how you might make improvements to it.
In your letter, you should describe who you are and what your business is and does, and how it might be of value concerning usage by the potential customer. You then ask them politely, in the letter, for an opportunity to discuss those things with them.
Via clicking on the following links, you'll find samples of ways that you might draft such a letter that you might then tailor to meet your needs.
Sample Business Letters and Forms
Free Sample Sales Letter: Example of How to Write a Persuasive Business Marketing Letter
Introducing a sample introduction letter template tool to assist leaders.
Letter Samples - Free Letter Templates - Personal and Business Letter
Sample Business Letters and Forms
Idea Cafe Small Business Archive: "Company introduction letter"
Introduction Letters
Sample business letters by Quazell
Business introduction letter... Here's a sample business introduction letter.
Mid-career Job Offer Letter Sample: Introduction and Sample Mid-career Job Offer
As far as the advertising is concerned, we can work on that with you, but we'll need to know more information as to the specifics about your business.
Such as:
Specifics as to everything that you can provide to potential customers.
The type of customer(s) to whom you would like to target the advertising.
Whether you make deliveries and/or shipments to the customers.
Your hours of operation.
Etc.
Thanks!