Adding another user or shared mailbox to your Outlook 2010.

1. In Outlook, choose the File tab, then the Info section (this should be the section you see by default). Choose Account Settingsthen Account settings, again.

Image of Outlook 2010 File tab with Info selected and Account settings highlighted

2. On the Account Settings window, choose the Data Files tab. Select your primary mailbox in the list (it will most likely have your name) and click the Settings... button.

Image of Account Settings window with Data Files tab selected and settings highlighted

3. In the Settings window, choose the Advanced tab and then click the Add... button. 

Image of Settings window with Advanced tab selected and Add... highlighted

4. In the Add Mailbox window, type in the name of the mailbox you want to open and click OK.

Note: If there are several mailboxes that match the name, you will be presented with another window asking you to pick the correct mailbox.

Image of the Add Mailbox window

5. In the Settings window, you will now see your mailbox. Click OK.

Image of Settings window showing the added mailbox

6. In your navigation pane, you should now see the mailbox. Click the arrow that is immediately to the left of the name to expand it. 

Image of Navigation pane with new mailbox highlighted