You can see the office contact information for the office selected to the left and the people who work there i.e. who are associated with that specific office. Think of the bridge and mortar world. Who goes to the office to work ever day? What is the address of that location? This is the information you should put here.
While Chronicle does not have a field for the web site address, you can add it to the notes section of either the phone number or the main email address. And or you could make it a survey answer so that you could pull up the website address in reports.
When associating people to the location you can either add a new person, associate a person who is already in the data base. If someone no longer works at this location you can disassociate them. This does not remove them from the data base but rather removes the association to this location.
When you have selected a person in the list you will see their InfoPanel to the right of their name. And if you have checked "use office address" you will see not only their personal contact information but also their office contact information.
If you added an email address for this office, Chronicle by default is going to add an "office contact". This will be done because Chronicle can only email a person. The generic Office Contact allows Chronicle to efficiently email a general email address.