How do I setpup a nailbox  in Outlook7 to share with other staff members?

I recommend you ask your Exchange administrator.

Hi,

Here is an article about how to create a shared mailbox.

http://technet.microsoft.com/en-us/library/jj150570(v=exchg.150).aspx

On Outlook client, we can share folders and calendars with others, even delegate access to others.

Refer from.

https://support.office.com/en-us/article/Manage-another-person-s-mail-and-calendar-items-a9596f29-2408-4a17-a2a8-6d009eb4b572?ui=en-US&rs=en-US&ad=US

Best Regards.