Often asked question – simple solution:
As always – create a child theme to work with – do not edit Twenty Eleven directly.
Edit header.php in the child theme, and locate:
<h1 id="site-title"><span><a href="<?php echo esc_url( home_url( '/' ) ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?>" rel="home"><?php bloginfo( 'name' ); ?></a></span></h1>
To add the logo image in front of the site title, change the section to:
<h1 id="site-title"><span><a href="<?php echo esc_url( home_url( '/' ) ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?>" rel="home"><img id="site-logo" src="<?php echo get_stylesheet_directory_uri(); ?>/images/site-logo.png" alt="" /><?php bloginfo( 'name' ); ?></a></span></h1>
To replace the site title with the logo image, change the section to:
<h1 id="site-title"><span><a href="<?php echo esc_url( home_url( '/' ) ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?>" rel="home"><img id="site-logo" src="<?php echo get_stylesheet_directory_uri(); ?>/images/site-logo.png" alt="" /></a></span></h1>
Important: to keep the logo image from stretching, you need to add this to style.css of your theme:
img#site-logo { width: auto; }
In this style, you can add more formatting such as padding or margins for the positioning of the logo.
The above code assumes that the logo image site-logo.png is located in the /images folder of your theme.
You can use any other absolute path to the location of your actual logo image instead:
src="http://anyabsolutepath/logo.jpg"
http://www.w3schools.com/tags/tag_img.asp

Thank you so much, you have saved me a lot of time :O)
Hi.Am not so good in programing. could you help in uploading log onto my site pls..wwwkibsdeliveryservices.com.au.
will appreciate as much help as i can get.
Cheers.
you could join the WordPress support forum to ask your question there. or email me with a request for assistance. alchymyth@gmail.com
I replaced the code with
<a href="” title=”" rel=”home”><img id="site-logo" src="/images/site-logo.png” alt=”" />
I placed an image with the name of site-logo in public_html/images. When I visit the site I see a “place holder” for a logo with a red cross in it but no image.
Can you help me with this?
Regards, Oddur.
simply do not use relative image paths. use the code from the examples. or use the full absolute path (starting with http://.. ) to the image.
yes thank you I have used this code
Thank you very much, it is much better!
Hi, I read your interesting and useful articles, you are a connoisseur
tell me how to make a theme twentyeleven static?
Now it’s bad when the changes in the browser window on a small screen like netbook
if the ideas in my earlier post are not going far enough, please join the WordPress.org support forum and ask the question there.