Site upload, but says i ndont have an index.html

Hello. I have uploaded my site, but my main landing page is default.htm.
When I view the site I get a message You see this page because your website doesn’t have " index.php " or " index.html " file in public_html folder." I’m not sure how to create ad index file that will bring up my site.

Please advise

Change default.htm to index.html