You can upload a html file directly using cpanel (if it's small and plain text) ...
To upload a file through the built-in cPanel File Manager:
Login to cPanel and open the File Manager.
Choose to open Web Root and Show hidden files.
In File Manager click the Upload Button
Navigate to the folder where you want the upload to be located.
Click on the Upload icon from the top toolbar
Click the Browse box (some web browsers change this to similar words like choose or select)
Locate the file on your computer that you wish to upload.
Select the file and it will automatically upload.