Here is the short version: Login, Find your listing, click Claim...

Here is the detailed version... To claim your listing so that you can update it with more details, video, and pictures:

1. You must register so you have a valid username and password to login with, if you have not already.
2. Click the Login link top right and the login using your username and password.
   
3. Browse the Directory or use the Search to find your listing.
4. Click on your listing to open the full page for that listing.
5. Look for the action menu.  It is below the listing details and is above the map section.
6. Click "Claim"
   
7. Enter a message for the administrators stating this is your entry, include a phone number if you feel there might be questions.
8. Click Claim Listing button.

Then What?

An administrator will then approve your claim, usually within 1 business day.  You will be notified.

Once your claim is approved you can login, find your listing, and click EDIT next to its title to make changes.