Well, I know document.getElementsByTagName("BODY").style.backgroundImage = "url(link)"; would work. Perhaps you could work form there on? I am afraid I don't know how to manage the uploading of an image and all that.
Not sure you would get only 1 'body' from your tag (may get an array with 1 element). Shouldn't you use document.getElementsByTagName("BODY").style.backgroundImage = img ??? Also, not sure if the image would be shown if it is not loaded yet. You may need CSS for it.
for logged in users, the uploaded image url is stored in the db and put into style.css.php on each login from either cookie or session details
of course the first lines of style.css.php look something like
in the above case, the stylesheet is linked as <link rel="stylesheet" type="text/css" href="http://www.mysite.com/style.css.php"> the gziphandler speeds download of the css file, which is a great candidate for compression the file is large, and contains much repeated strings
Thanks for the help. I'm very interested in the following: the user clicks on the change background button and the user's my computer folder opens then he chooses image file from his computer for background. I need this because for the site I'm working on I have to make upload images option and the upload will be from the client hard disk.