problem in drop down list in asp.net

Question

i have two dropdown list first dropdown list id is state and second list id is distic, i wanted to hide second dropdownlist and it is display only when user select any state name in first dropdownlist , and second list show the distic name according to the  selected state name in first list , example i have state name like hp, punjab, delhi, up etx , and second lise have , distic name accordingly , if user select punjab than only punjab's distic name will show .
can anybody help me for this