Tip: to import an address book from CSV or VCF files (aka "vCards"), click on "Others". (Use it for contacts exported from Outlook Express, Windows Live Mail, Microsoft Outlook, etc.) Click "Browse" to pick a file from your computer, and double-click on it..
Tip: if you get a "We had trouble reading contacts from the following accounts" error message, click on the "Try Import Again" button - but first check the number of contacts imported.