Next, open a blank page in a generic editor, for your CSS file.
Type in a few CSS specifications, and then save the file.
Point your browser at the HTML file you saved, and open it in the HTML editor.
Look at the HTML source using the tab at the bottom of the editor. Find the tag, near the top of the file.
The way the link is set up now, it says to look for the CSS file in a subdirectory of the one containing the HTML. We have probably saved our style sheet in the same directory as the HTML.
We must change the HTML so that it points at a style sheet in the same directory as the HTML page.
Voila'! The style specifications we make in our CSS sheet now apply to our HTML.
Subsequent changes all continue to apply - we are done with the hard part.