If you look around, you'll notice that everything is labeled. From a small jar to a large office desk, each and every item is bound to have at least one label. Labeling things is useful, easy and practical, and the applications are virtually endless. You can find a wide variety of labels available on the market, in different shapes and sizes, styles, designs, colors, materials, templates and so on.
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.