Dujiangyan irrigation visiting

1) If I take bus from Chadianzhi /Xinanman bus station to DJY, which point should I drop off and how do I get to the entrance of DJY Irrigation? Do I go to the same place where I drop off earlier to take the bus back to Chengdu?
2) If I take bullet train from Chengdu North train station, how do I get to the entrance of DJY Irrigation after dropping off at DJY train station?
Thank you.