I would like to go from Zhongshan or Hongkong to get to Changsha, how do i travel easiest there

From Zhongshan, you can take train via Guangzhou to get to CS. You can take bullet train from Zhongshan to Guangzhou South Train Station, then take high speed train from this station to CS. From Hong Kong, you can take train or bus to Guangzhou first, then go to Guangzhou South to take the high speed train.

Thank you! I´ll try that!