When it comes up it will list a topic in the Horse Forum such as Horse Training or Horse Breeds or Western Riding. Go to that topic and when you click on it a box at the top of that page will say "Catch the Carrot". Click on it and you caught it!
Well, that was a bit stingy, but I guess that is how you get over 2000 carrots. The carrot locator shows you what category the carrot is hidden in. If it says, Horse Training, go to the list of categories and click on Horse Training and there should be a "catch the carrot" box if you got there first.