Just enter the gate of Tianjin Railway Station, all your luggage must be checked by security machine. The ticket counter on the your left side, the big screen in the middle show schedule time for the bullet train ( C .... ) to Beijing ( English and Chinese ). The big problem is most staff can not speak english but do not worry you show these chinese letter to any staff to help you to buy tiket 北京南站 (South Beijing Railway Station).
There are 2 kind of fares : economy ticket 58 yuan and first last ticket 65 yuan. On the ticket show the seat number, time departure and number gate to enter the train. You should find the waiting chair near the gate for easy to hear the notice for entering the train before 15 minutes to depart time. Notice verbal in chinese and english. Just 30 minutes you will arrive Beijing.
From Binhai Airport you should take the shuttle bus to Tianjin Railway Station 10 yuan / 1 tiket, the bus stop at the arrival gate at the airport, you buy the ticket at the door of the bus ( show the man at the bus door these letter 天津火车站 ( mean you want to go tianjin railway staion )
I have just finished my trip to Beijing 2 days ago, this is my experience for everyone !!! You can contact yahoo.com|thanhnhannt for more detail if I can help you !