Hi,
Well if you open the HTML document with Wordpad, Notepad or similar text editor and highlight and copy everything within the <body> </body>
tags and then paste it into the HTML (not the Visual) editor in WordPress, and click ‘Publish’ or ‘Save’ you will get some semblance of the original document. It will probably not be exactly the same, however, and you may well need to make changes, especially to image link addresses for your images. If you are using inline styles then you should be alright formatting-wise, but otherwise the page will appear based on the stylesheet of the WordPress theme you are currently using.
All the best,
Rory. ??