Visit website and click on "Join" link under "Bounty & Airdrop" menu item. Register and verify your email to access dashboard. You'll get 500 tokens upon registration. Enter your ETH address and scroll down to submit your Telegram & Twitter handles. You have to join Telegram (2000 tokens) group and follow on Twitter (2000 tokens). You'll get a total of 4500 ABT tokens (worth ~$45)
You can get 50 additional tokens for every person you refer.