The heading of a professional or business letter consists of the return address of the person who is writing the letter, but not the letter writer's name. The name is placed under the close of the letter, and thus is not required in the heading. In addition, the date of the letter should be included under the return address.
Place the return address of the sender at the top of the letter. Do not include the name of the sender. Place the address at the top of the letter and center it; you can start with a company name, if appropriate, with the return address just under it.
Spell out the words and do not use abbreviations in the address, except for the state, for which you may use the United States Post Office standard abbreviation for the state. This is done with two capital letters and no period (for example, AK for Alaska). The words Street, Avenue or the like are fully spelled out.
Place the date directly under the return address and align it to the left margin. Most professional letters use a full block style, in which all elements except the aforementioned return address are aligned to the left margin, and not indented. This includes paragraphs.