To update/add your guild to this list, you need to visit that guild's roster page by searching for the guild here.
You will first need to register on the site, as well as 'claim' a character that is in the guild you wish to update. Once you have done that, you
can access the guild update area to input dates for progression.
Alternately, you can email updates to progression(at)warcraftrealms.com.