On MSWindows, if you have a code editor installed (even just notepad), right-click on your .html file and point to "Open with EDITOR", where EDITOR represents the code editor you have available in the sub-menu (Or your preferred editor). It will be listed upon pointing as above. Click on your editor's name in the menu.
**Ok, just for an aside: You notice that from the moment you save a text file as .html, it bears your browser icon. If you double-click the file, it will open in the browser and you can't edit the HTML directly there. Right-clicking will give you the option to choose what installed program to open the .html file with, your browser(s) included.