Please solve my quary,

Hi all,

i have created a web application  and now i have added a dropdownlist in my application.In dropdownlist i have added diffrent language like hindi,franch, spanis, so on ,now i want that if i  select any language pages should be display in that language,,,,if i select franch ,pages show in french language.. for exaple ,, see facebook in that if we select any language , pages display in that language.. please help me wuth source code and example..it is very important for my project 

Thanks in advance.