Web browsers aren't designed to display spreadsheets by default, there are two workarounds that you can use to display spreadsheets on your website.
Option 1 is to convert your spreadsheet into a Google Sheet and then embed it into your website. You can get more info on doing this from Google here: https://support.google.com/docs/answer/183965?hl=en&visit_id=636711788800449417-3481761003&rd=3
Converting to HTML
You can alternatively save the spreadsheet as a CSV and convert it to HTML using a tool like this: http://convertcsv.com/csv-to-html.htm
Once you have the HTML you can go to any page on your website, switch the editor to "Code View" and post your code in, when you save you'll have your spreadsheet on whatever page you put it on.