Method 1: Modify xx.html to page-xx.php and upload it to your current theme directory;
Create a page with an alias of xx in WordPress background and publish it. You're finished.
Note: The created page alias must be the same as that after page-. Or change xx to your page ID in step 1.
Method 2: Modify xx.html to page-template-xx.php, and then add:
& lt? PHP/* Template Name: xx Page Template */? & gt
Then upload it to the theme directory you are currently using;
Create a page with alias xx in WordPress background, select the page template as the xx page template created in the first step, and then publish it, and you're done.
If the added page is the first page, you can set it in Settings >; Reading > Settings in the homepage display sets this page as the homepage.