When you want to call up that template, here's what you do. In your MS Word, click on 'File' (take note that you don't click on the File icon, but the word, 'File.' When you do so, a dialogue box appears from where you can choose the template you just created.
That's how to create a business letterhead in Word. Now, how do you monetize this new_found knowledge? Offer to your community a letterhead printing service. You can offer to design a logo and print the letterhead. Don't know how to design? Outsource it and then mark it up. Then go to a printing press, get a quotation to print letterheads and then mark it up. But don't mark it up too much. The point is to get as many clients as possible even with a small profits. Several small profits will always add up to big profits.