Centering for content?

[ASATopGun]

Im tryign to center my content area inside of my two sidebars but im entering something wrong apparently. Heres the two pics

http://i.imgur.com/63dyTC6.png

http://i.imgur.com/U8g3Esa.png

 

[chrishirst]

Set margin: n px|em|% auto; on a block level element that is less than full width.

 

[ASATopGun]

Okay what yoiu just said confused the heck out of me

 

[Edge]

Okay what yoiu just said confused the heck out of me

e.g.
.foo {
width: 90%;
margin: 0 auto;
}