HOW TO TAKE A BUS FROM BEIJING CAPITAL AIR PORT TO RAILWAY STATION? THANK YOU

Firstly, I'd like to tell you that the Airport Shuttle Bus Line 2 can take you to the Railway Station.
You can buy the ticket at:
T1 -- inside Gate 7 on the 1st Floor;
T2 -- outside Gate 9-11 on the 1st Floor
T3 – outside Gate 7 on the 1st Floor
By taking the ticket, you can go and catch the bus at:
T1 -- Gate 7 on the 1st Floor;
T2 -- Gate 13-18 on the 1st Floor;
T3 -- at the West Gate on the 1st Floor