You will need to access your website files in order to add the html file. You can do this using an FTP client or you can use your web host’s interface in order to get to website files saved on the server. The procedure to access the files using your host’s interface may differ based on your host. If you are using a cPanel based interface, access the File Manager, then go to the folder where you have saved your WordPress installation. Upload the HTML file and then follow the rest of the instructions that Google provides.
If you have any further questions or comments, please let us know.