If you save a file with the extension .html, the next time you go to open it, it will most likely open in a browser - as this is the default program for viewing html documents.
If you want to edit your html source code, all you have to do is open the same file with a text editor.
I use Sublime Text Editor, but any old text editor will do.
Just save the changes you want to make, an open an instance of that file in a browser and you should see the changes you've made.
