Steps to Import (merge items) from a .pst:

1. With Outlook open, select File - Open - Import in upper left corner.

2. From the Import and Export Wizard window select Import from another program or file, then Next.

3. In the next window select Outlook Data File (.pst), then Next. You may need to use the scroll bar on the right to find this option.

4. In the Import Personal Folders window, select Browse and locate your desired .pst file, then select the Next button. If a password was set on the .pst file when it was first exported, you will be prompted to type in that password.

NOTE: The three Options in this window allow you to change what will happen with any duplicate items (email messages, calendar appointments, tasks, etc.) that may exist if you are importing into an existing list of folders. If you are not sure about duplicates, select the second option, Allow duplicates to be created, to be safe.  



5. At the next window, make sure that the topmost heading of the Outlook Data File is selected, and that the Include Sub folders box is checked to include all items from the .pst file during the import.

6. Leave the default Import location selected, Import items into the same folder in: <User Name>, to merge email messages, tasks, etc. into the same folders of your current Outlook profile. Select Finish. 

7. Outlook imports the email, appointments, tasks, etc. into your current profile.