Go to:
http://support.microsoft.com/default.aspx?
scid=kb;en-us;258619
Be sure to creat the folder in a Personal Folder and not
in a Mailbox.
Step 1: Create the Group Calendar
On the File menu, point to New, and then click Folder.
In the Name box, type a name for the folder.
In the Folder contains list, click Appointment items.
In the Select where to place the folder list, click a
location for the folder.
Step 2: Publish the Net Folder
In the Folder List, click the group calendar folder that
you want to share.
On the File menu, point to Share, and then click This
folder.
Click Next, and then click Add.
In the Type name or select from list box, type the names
of the people that you want to share the folder with.
After you enter each name, click To.
After you type all of the names, click OK.
Click a name in the Member List list, click Permissions,
and then assign a level of permission to that person. You
can click several names to give them all the same level of
permission.
Click Next.
Type a description for the folder, and then click Finish.
An automatic invitation is sent to each of the potential
subscribers. They must click Accept in the invitation to
subscribe.