You can't post a pic directly here anymore so you need an 'image hosting' service. I use tinypic.com. It's free and easy.
Click "Choose file," then "Upload now," then copy the link labeled, "Direct Link for Layouts."
You paste that link into the "Insert Image" box on your header, click "Insert" and the pic should appear.
I second that for tinypic.com
Choose a file, upload it, then right-click to copy the link labeled, "Direct Link for Layouts."
You paste that link into the "Insert Image" box on your header, click "Insert" and the pic should appear.