Step 1: Click the Address button from the top menu. Select the Address Book from the dropdown.
Step 2: Click the Import/Export button.
Step 3: Select the appropriate format for the address book that you are trying to import. (CSV and VCF are the most common)
Step 4: Find and select the CSV or VCF file from your computer and then select Next
Note: If you wish to over-write the existing address book, check the appropriate box
Step 5: Leave all the defaults in place, then click Next
Step 6: Again, leave the defaults, then click Next