How can I get the entrance ticket to an attraction of Lintong ?

In the message "There are free shuttle buses between Xian North Railway Station and the museum. They are scheduled from the railway station from 08:00 to 16:00 and return from the museum during 10:30 and 19:30. The whole journey takes around an hour.
Note: To take the free shuttle bus, you will get a boarding pass/card by showing your train ticket on the arrival day and the entrance ticket to any attraction of Lintong. Upon arrival, you can buy the tickets of Lintong attractions at the Tourists Service Center on the underground floor of the railway station."

I wonder that
1. How can I get the entrance ticket to an attraction of Lintong ?
2. All tickets to the attraction of Xian, does there have a place to sale these tickets, where can I buy. Or I have to get the entrance ticket at there place.