full-width page [Creating own page template, cont.]

what theme is your question referring to?

what exactly is the problem?

make sure to work with a child theme for this kind of customisation:

http://codex.wordpress.org/Child_Themes

if you make a page template using a copy of page.php, it automatically does have no sidebar and only one column – the rest is adaptation of the css to stretch the content over the available space.

http://codex.wordpress.org/Pages#Page_Templates

the template file name will be referenced in the ccss class output by body_class(), so you can use that to selectively make new styles for the full width.

http://codex.wordpress.org/Function_Reference/body_class

please use a tool such as Firebug to identify the involved css selectors.

http://getfirebug.com/

please post a link to your site, with the child theme and page template activated, pointing to a page using the page tempalte, if you would like to get some more suggestions.