How to pass data from View (DropDownList) to Controller in ASP.Net MVC

Hello, i am new to mvc, in my project in a view i am opening a modal popup window. in that popup i have added multiple dropdown boxes. i have bind those with the controller and able to display data in those.

one of the drop down is State and another one is City. city accepts stateid as argument to load data. so when i select state drop down, the selected if should be passed to controller to load city drop down. from one of your post i am able to get the value of selected item but i don't know how to pass value to controller..

Your reply will be very helpful.

Regards,

Savan Parmar