1- At the top of the Ribbon of Outlook, click File
2- Choose Open> Import. the wizard will start
3- In Import / Export Wizard, click Import from another program or file and click Next
4-Select Outlook Data File (.pst) and then click Next
5-Click Browse, then the PST file to import, and then click Next.
Note: Under Options choose whether you want the information imported to replace duplicate items already in Outlook. Otherwise, click Do not import duplicates
6-If the Outlook data file (.pst) is a password is assigned, you will be prompted to enter it, then click OK
7- Set the options to import items. Choose Filter if you want to import only some e-mail messages. Choose the More Choices tab if you just want to import e-mail messages already read or unread.
It is usually not necessary to change the default settings. Automatically selects the root folder, usually Personal Folders, Outlook Data File or the e-mail address.
8-The Include subfolders is checked by default. You will import all the folders in the selected folder.
Select one of the destination options:
Import items into the current folder: The data is imported into the selected folder.
Import items into the same folder: the data is imported to the destination folder with the same name of the source folder, such as Inbox to Inbox. If a folder does not exist in Outlook, it is created.
10-Choose File. Outlook sends immediately import the data. When the status disappears, that the procedure was completed.