How can you change Youtube's channel background picture?...?

When I went to the change design section, it just asked me about Background image... I browsed on my computer, and clicked on my chosen photo... But, then, when I opened my channel, there was no background picture... What's wrong??How can you change Youtube's channel background picture?...?Go to Account -%26gt; My Account -%26gt; My Channel -%26gt; Channel Design -%26gt; Advanced Design Customization -%26gt; Background Image -%26gt; Browse -%26gt; select Image -%26gt; upload