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.
Why create one? _ "Re_inventing the wheel", is no fun. If you work for a single organisation it's likely that your templates could last a long, long time with no need to go back to the design board every time you are asked to create a new manual or user guide. When you work for yourself it's a great way to show clients that you have the skills they are looking for without breaking any confidentiality clauses with your existing clients, and with just a little bit of luck they'll adopt your method of working so you can continue to recycle your past efforts too.