Just a minor point arising from the above: There seems to be some confusion above as to whether the filr type (extension) should be .htm or .html

Both will work in a browser (assuming the file content is in HTML format), but it's important to make sure you use the right one for what you are doing. If you have a link to your HTML file from another webpage, the link needs to know which it is named as (blah.htm or blah.html), so you will need to make sure if you change the file type from (say) .txt to .htm or .html, that you set it to the correct one of these two possibilities, or the links to your page won't work.