I have been struggling with this for over a month. I have gone through all threads but all in vain. from one of the threads i learned how to change the background color of a single widget but when i use that, nothing happens. look at the css i use and tell me what is my mistake.

div.text-26 {
background-color: #EEEEEE;
}

I am trying to color the widget which contains authors bio. http://www.christiantruthcenter.com

I am trying to color the widget which contains authors bio

which widget might that be?

In the side bar, it is the first top widget. The widget contains a picture of myself and a small bio

the 'text-26 is the ID not a CLASS - you need to correct your syntax

From a previous thread i read that we use the widget id and that is what i used. which syntax do i use then? give me an explanation on this.

You do use teh ID, you just have teh syntax wrong. Go read take a CSS tutorial and see teh difference between ID and CLASS syntax. A good tutorial is at htmldog.com