Click on the the template. At the bottom right of the dialogue you'll see two options: 'Document' and 'Template'. If you want to use the letterhead to send as a document or letter, choose 'Document.' If you want to edit the template, choose 'Template.' When you choose 'Document,' it gets saved as an MS Word document.
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.