Can I convert an existing PNG file that I have over to an HTML file?
Since PNG is an image file and HTML is a data content specification, you can't.
You could, though, display that PNG file in the HTML file, using basic codes
You could also use advanced software like the free Gimp ( http://www.gimp.org/ ) or Adobe Photoshop to export the image into stylesheet layers (
Or maybe you actually need a program like this one: http://www.engr.mun.ca/~holden/png2html.html ?
To embed the image in HTML you can also use this online tool: http://www.greywyvern.com/code/php/binary2base64