You can opened an account with Photobucket to upload your images. When you have done that, click on the "choose file" and look for the blinkie in your hard drive. Make sure you are in your album in PB and hover over the image. This will give you a selection of codes. Highlight and cope the IMG code.
Then go into your User CP - Edit Signature and place code into the box and save signature. To centre the blinkie, highlight the whole code, and click on your centre button.
Hope that helps hun xx