[GrannyGrump]

Try using <hr /> (horizontal rule) for simple straight lines.

You can style it in the CSS stylesheet to be any thickness you like, or a double line, etc, etc.

In the stylesheet, something like:

hr 
{border-top: 1pt solid; margin-top: .5em; margin-bottom: .5em}

or

hr
{border-top: 4pt double; margin-top: .5em; margin-bottom: .5em}

}

The greater the number of "points" (1pt, 4pt, 10pt), the thicker the line.

Then in the HTML, you could put something like this:

<h2>CHAPTER ONE</h2>
<hr />

W3schools have very helpful tutorials to learn about html and css.
for instance, a quick "try it yourself" tutorial on horizontal rules can be found here: https://www.w3schools.com/tags/tryit...hr_default_css


And JSWolf is correct in pointing out that the fancy swirly decorated lines are usually pictures.