Accessing Shared mail box in google mail services through Imap



I am having shared mail box which can be accessed through my google account.Actually this is a enterprise mail account. How can i access the shared mail box using Imap protocol.
In the MAIL>IMAP>Get IMAP mail messages activity i could see only email and password. With these two i cant access the shared email box. Is there any other means to access the shared mail box?