Page content width

please create a child theme https://codex.www.ads-software.com/Child_Themes of Twenty Eleven before you continue with your customisations.

it is important to have an unedited default theme (Twenty Eleven for wp3.3) in case of problems. a child theme also helps to keep the cusomisation during an upgrade.

once you have your child theme up and running, the forum should be able to help you with your question.

Um, my theme isn’t edited though. I have two plugins installed called

Pixelentity – Estro Slider
and
WordPress Post Tabs

and the only thing that’s changed in the theme is adding one piece of code in page.php for the slider to appear above the menu and that code is…

// alternatively, if the above doesn't work for you (code in included in a function)
$GLOBALS['peEstroPlugin']->the_slider(1);

And that does not replace or change anything. Aside from adding that on the page.php file, nothing else has been altered in the theme files.

Um, my theme isn’t edited though.

fine – before you start editing, please create a child theme.

Ok so once I create a child theme, what should I edit to try and make the content area wider? Is there a specific line of code etc?

create the child theme first;

please post here again once your child theme is working.

someone might then be able to answer your question.

You’ll need to modify the css file. Search for the class .entry-content. The width of that div is set to 68.9%. You can change that to 100% for it to take up the width of the content area.
Hope this helps.

In your css:

.singular .entry-header, .singular .entry-content, .singular footer.entry-meta, .singular #comments-title{
     width:100%;
}

It swill fix your issue.