Exchange 2010 - where to modify permssions on a shared calendar?

Drawing a blank.  How/where do I modify permissions on a shared calendar that I dont have access to?  We use Exchange 2010.
Our Engineering Dept has a shared calendar they all use...  they just hired someone new and I am trying to get them connected to the calendar and give them edit permissions...but I cant seem to figure out where to do that for a calendar in Exchange.  I dont have access to the calendar myself, but have access to exchange.

One of the engineering employees is here and i tried to right click the calendar from her Outlook and access permissions.  I could do that but it wold not let me edit the permissions and therefore I could not add the new employee.

I am assuming there must be a way to do this from Exchange, but I cant find where.