When you arrived, look for a taxi to take you to the train station (huoche zhan in Chinese). There are two train stations in Guangzhou. The other one is for Hongkong. It is called East train station ( Dong huoche zhan). If you just say huoche zhan, he will take you to the train station for cities in the mainland China. To be sure, tell the driver that you will go to Changchun (Dao Changchun). If he can't understand you, call your contact in the school(your employer in Changchun) to talk to the driver.

Be careful when you get a taxi because some of the drivers will take advantage. Ask the people in the airport where to get taxi.

P.S. I wonder if you know some useful Chinese words. It is very useful if you know some.