Call SubRoutine from Onclick event within Area Shape Attibut

Question

I am new to C# and am trying to call a subroutine from an OnClick event within an Area Shape attribute. I would like to be able to click on a county within a state map and have data from a database populate on the webpage based on the county clicked. Is this possible in C#? If so, would someone be kind enough to provide me with the proper syntax to call the subroutine as I have not been able to accomplish this task.

<area shape="rect" coords="329,259,379,309" href="" onclick="Subroutine()" alt="County Name" title="County Name"    />

Thank you in advance for any assistance that you might be able to provide.

Todd