Raul Said:

writing business letter, want to put sent Certified - where would that go?

We Answered:

I believe that would not be stated in the contents of the letter. That would be on the outside of the envelope, and handled by the Post Office

Marshall Said:

Writing business a letter to a business?

We Answered:

I would start by getting a template or format then reword this to fit your needs. Some good templates are located at office.microsoft.com, search for business letter template.
Your outline should consist of who you are, what you can do, how much it will cost them, what qualifications you have to prove you can do what you say you can do with reliability. Do you offer warranties if the items break etc… Why you are better than choosing bigger companies and so on.