First off you need a photo hoasting site, I use
http://photobucket.com/
To upload an image:
Log into your Photobucket account.
Click the 'images from my PC' tab at the top of the Upload Panel. The tab will be labeled 'images from my Mac' for Macintosh users.
Click a 'Browse' button and select an image from your computer.
You may add a Title for the image in the box below the image file name (optional).
Click the 'Upload' button.
When the image upload has successfully completed, you will be placed in the image tagging screen. Tags, titles and descriptions can be added or modified from this page. This process can be skipped for the current upload or the option can be turned off/on for all uploads within the upload ‘options’.
Once this process is completed, the image will appear in the thumbnail size in the album.
Click on the thumbnail & it will appear in full size, click on EDIT & resize it to the correct size for the SCN siggy allowance.
You need to choose the IMG taged image, copy & paiste in to you user cp siggy bit.
Job done........