<SPAN STYLE="BACKGROUND-COLOR: #CC0000">This text has a red background</SPAN>

This text has a red background

You can also use a picture as a background to your text like this

<SPAN STYLE="BACKGROUND-IMAGE: URL(http://www.yourimagehost.com/yourname/yourpicture.jpg)">This text has a background picture</SPAN>

This text has a background picture

Or this

Here is some more text with a background picture

You will find the browser safe colours by clicking here

You will find some backgrounds by clicking here