HTML for adding a background color?

Answer 1

It's not HTML. Background color is a CSS style. You need to put in either a stylesheet, or attach the style attribute to the tag whose background color you're trying to set. For instance:

<p style="background-color:blue;">This paragraph would have a blue background.</p>

Colors in CSS can be set using names (there's 170 or so of them)

Via a hexadecimal RGB value:

<p style="background-color:#b3b3b3;">This a meduim gray. The pairs of hex digits correspond to RGB.</p>

Using RGB directly:

<p style="background-color: rgb(179,179,179);">This is the same color as #b3b3b3</p>

And using RGBA (which gives you an alpha channel, letting you set transparency)

<p style="background-color: rgba( 179, 179, 179, .5 );">This paragraphs background color would be 50% transparent.</p>

Answer 2

To give a background color to a HTML element, add "background-color:(color)" to its style-attribute.

Example: Text with red background