1. In your yahoo account - Click the icon and then click 'Download File' to open the attached signature file.

2. Click 'Open' (or 'Save' the file and then open it) to view the signature in a new browser window.

3. When the new signature window appears - Hold the 'Ctrl' key and press 'A'. ('Select All' shortcut)

4. When the signature is selected - Hold the 'Ctrl' key and press 'C'. ('Copy' shortcut)

5. Go Back to your yahoo account - Choose 'Mail Options' from the 'Options' menu.

6. Click 'Signature' from the menu. And make sure 'Show a signature on all outgoing messages' is choosen.

7. Make sure the editing tool bar is shown. If it's not, click 'Rich Text' in the upper right corner.

8. Click the editing window - And then, hold the 'Ctrl' key and press 'V'. ('paste' shortcut)

This is how the signature will appear in the window.

9. To complete the process, click 'Save Changes'.