I wouldn't entirely trust that first link, as they only talk of absolute image URL's. And other explanations are either inconsistent or even wrong.
The second link again uses only absolute image URL's. This time the url to the image needs to be relative to the file in which the CSS is defined.
So, looking at the code in the attached file, if your HTML file is on the Desktop and the image is in the folder Pictures, which in turn is contained in the folder Madhav_ji, then your img tag should look like this:
<img src="Madhav_ji/Pictures/620443.jpeg" alt="">