How To Add Full Width Post Template In twenty eleven theme

This has been answered quite a number of times – here’s one:

https://www.ads-software.com/support/topic/twenty-eleven-make-page-default-template-full-widyh?replies=5

Thanks For Reply,
I have already Read Above Link, But I am taking about “Fullwidth post without sidebar” in twenty eleven theme NOT “fullwidth page”

thanks

First you need to create a child theme. How comfortable are you with using PHP, CSS & HTML?

Thanks for reply,

ok after making child theme thet, And I am Little bit comfortable with using PHP, CSS & HTML!

A single post does not have a sidebar in Twenty Eleven by default. So all you need to do in your child theme is re-style the single Post page using CSS. Try using Firefox with the Firebug add-on for this kind of CSS troubleshooting. Or use whatever developer tool is available in your web browser.