First u go on my home page on scratch , dont go right to the project i have just showed u, press right click on your mouse and click on 'Save image as' and write the picture of the image like e.g. 'clank'. And go change your picture by browsing it and you'll see your pic you have saved, click on it and update it on your hompage and there u have it. quiet simple and trust me it will work.
