I want to make the main area bigger

I want to make the area which contents the products and the left and right collumns bigger and eliminate the background space which is so big.
So i would like to do it like this:
http://www.survival.gr/
instead of this
http://www.opensourcecms.com/demo/1/96/Zen+Cart

Where is your install?

i have it in local machine so it is not visible in the internet yet.
But is kind of like the default template of the zen cart.
I want to modify the template not to use an other one.

Take a look at the Holzheimer site in my sig. Is that what you're going for? If it is, go to admin>configuration>layout boxes controller and set the following:

Column Width - Left Boxes 250px
Column Width - Right Boxes 1px

You can adjust the size as you wish.

Then go to admin>tools>layout boxes controller and either turn off the sideboxes in the right column and/or change them to the left column (it'll be clearer once you see the settings).

Assuming that you are using the latest release of ZenCart as you did not provide any information

Find the stylesheet.css file that your active template is using and look for

#mainWrapper {
	background-color: #ffffff;
	text-align: left;
	width: 750px;
	vertical-align: top;
	border: 1px solid #9a9a9a;
	}

You can increase this value or make it a percentage

Sory :D yes i use ZC 1.3.9.
I will try it and i post a feedback :)

Thanks. it works :)
I used the method with the CSS

Hi all,

I have v1.3.7 and I just increased MainWrapper width to 960px but the rest of the content did not expand to fit - any ideas?

TIA

Isaiah