Blinkbid supports the vCard standard for importing contacts from other address books so you can bring al your old friends to the party.
Click the Expanded View button in the address book window.
Click the Import vCard button and locate the vCard file you want to import on your computer.
You'll be reminded that the contacts being imported will be the active set in the window.
After you import your vCard the list that is displayed is the imported contacts only. You can now assign some or all of those contacts to a group. Hold down the Shift-Key and click on the contacts to highlight them. Then click on the group you want to assign the highlighted contacts to and click on the assign button.