The first thing you'll want to do is test your countdown timer in a post, so you can just reply to this thread if you want.
After the 4th step of instruction #8, reply to this post and click in the area where you would normally type your message. Then on your browser click on the 'Edit' menu option that's on the menu bar of your browser. Then click on Paste entry that shows up in the dropdown.
Click on the Submit Reply button below the text you just entered.
If the Countdown Timer shows up ok, you just need to position your cursor in the Signature area on the page that pops up when you completed instruction #7. Then just do the same thing with clicking on 'Edit' in the menu bar and then clicking on Paste.
Hope this helps...
- Jim