When you're done, you can click on the 'Close' tab on the floating bar. The items in the header and footer will appear greyed out, but don't worry; this only means the they have been set. The cursor will then appear on the first line where you can begin typing your letter.
You can align your logo by clicking any of the alignment buttons at the menu bar. Press the 'Enter' key on your keyboard and you can type in your business address or a slogan. You can format the text just as you would when you're creating a MS Word document. You can choose the font, font size, color, align the text and even add graphic lines.