How to add Country,State,City through different pages

Question

I have one page Country.aspx through that i add country in my database...

I have another page name State.aspx through which i can add states in my database..

Now The country i have added in database through first page when i want to add states in 

database i want that added country to be shown in drop down list in my state.aspx page..

here in state.aspx page i have one drop down for country which i select and one textbox for 

state which i want to add...how can i add states with this....here when i click on save the state 

should be saved in database

how can i do that??

I have taken three different tables name country,state and city for that and 3 different pages 

country.aspx,state.aspx,city.aspx ..