when i click 1st dropdownlist value, open other dropdownlist

Question

 

 

i just want to open second dropdownlist when i click first dropdownlist value , their is no bind i can do ,ex:- when you click first dropdownlist it opens downwards just like that when i click first dropdownlist value it opens second dropdownlist downwards as same first ...... i hope you understand plz help  

 

see given links examples in  picture

 

http://www.c-sharpcorner.com/Photos/Photo.aspx?pid=1949