So when you say that you can't edit it, what is stopping you?
You can open the html page by right clicking on the file and selecting "Open with" and then selecting notepad. Yu can save it by selecting "File/Save".
When you save a new web page from notepad or save a page using "File/Save as", make sure that you put the file name in inverted commas, e.g. "webpage.html" or else Notepad will kindly add ".txt" to the end of the name, giving you "webpage.html.txt". That won't open in a browser.