hi Smeagol,
sorry, but that link doesn't work for me
To change your personal photo you have to go to "my controls" then look down on the left side where you'll see a bunch of links (sorry if you already know this, I don't mean to be repetitive).
Click on the "change personal photo" link and scroll down. You have two ways of posting a new pic, either by using an URL to a side where your pic is uploaded or by simply uploading it from your computer's hard drive.
If you could, take a pic of the error message that you get and post it here. You can do that by taking a screen shot of the error message by pressing on "Print Screen" button on your keyboard which is located approximately in the middle of it, then simply pasting (edit --> paste) into Windows Paint program (under accessories -> paint) and then uploading it to your next message.
Hope this helps.