You might be providing an extremely valuable service to many, many people. Your spreadsheet might free up peoples time from boring and tedious administrative work to spend more time doing things they love. It might help keep businesses above water or help them reach for new heights. Your spreadsheet might even help to create jobs or at least keep people employed.
You'll need to develop good marketing material. Things like demo videos, which you can find plenty examples on YouTube, screenshots, and keyword rich descriptive text help people find your spreadsheet and communicate the value that sets yours a level above the rest. Excelville.com actually allows you to upload your spreadsheet with all of this marketing material in an easily searchable and user friendly website.
Selling spreadsheets helps you to build a catalog of spreadsheets that you can take with you and use in various areas of your life. Spreadsheets built for sale are usually built for flexibility and would be customizable to your life, or job, or new life, or new job.
You'll need to find a way to make your spreadsheet accessible. You can build a website, which will require paying for a domain, hosting, site security, dealing with an internet transaction service, graphic design, content for the website, marketing your website, Search Engine Optimization, and all the other madness that comes with managing a site.
spreadsheet templates for tracking
uses of spreadsheet