How can we visit the Great Wall and or the Terracotta Warriors from Guangzhou?

Generally speaking, you can fly to Beijing to see the Great Wall and then fly to Xian to visit the Terracotta Warriors.
Bus 919 from Deshengmen Bus Station in Beijing can take you to reach Badaling Great Wall.
Tourism Bus Line 5 from Xian East Square of Railway Station can take you to reach the Terracotta Warriors.

Thank you James, your advice is just what I had hoped someone could tell us. I wonder what it's like travelling on buses in China?