From that search page, you can enter data into as many fields as you wish to find officials. For example, you can search for officials who are available on a given date by clicking on the "Who are available on..." field. You can also search for members within an association by clicking on the "Who are members of..." field.
Entering data into multiple search fields will filter your results even more than using just one field. That can help you find just the right official you are looking for!