After you are approved to join, a) follow the directions in the e-mail you are sent or b) login to Yahoo's Webring website and click on the name of your website next to "London After Midnight Webring"
This will bring you to the "Edit Web Site Information" page under the "London After Midnight Webring". If you've made it this far you are doing good.
Next, look to the left top where it says "Member Tools" and under "Member Tools" click "Get Navigation Code".
Finally, all you have to do is copy (Ctrl+C) the Nav bar code and paste (Ctrl+V) onto your website and you are done!