I'm not sure if I'm asking the right question because I don't know the terminology yet. I created an .html file in windows notepad and opened it on Firefox by double clicking the filename that I created. Everything was fine. When I closed the notepad text document .html, I was not able to reopen it, I was only able to reopen the html page on Firefox. I right clicked "view source code" and it was read-only, I could click the mouse on it but I couldn't add or delete any of the characters.
How do I access either the text file source in windows notepad or be able to change the source code?