Want to give different permission for employee and managers in team discussion board.

Hi All,

I am new to share point technologies . I am stuck in on place, there is team discussion board  in internal portal.

i want only managers can create new discussion and employee only should replay the discussion.so if when i apply read permission to employee they can not create team discussion  that is good but they also can not reply the discussion text .

for more understanding  please refer the  attached images. if you still not get it then please let me know 

Thanks,