ASPX Conditional Select Menu that Shows/Hides Form Fields

I have done a conditional select menu in JavaScript before, with the help of a Tutorial but now I would like to do this in C# ASPX.
STATEMENT EXAMPLE: If this option is selected, then display these 3 form fields.
I am trying to create a conditional form that has 3 types of options. When the user selects " Application Server" for example: It would display form fields that only apply to that type of server. If the user Selects " RackSpace Cloud " then the form fields below would only display if the user selects that option.
How would i do this?
<form runat="server"><select name="server_request_type" id="server_request_type" style="width: 200px;" runat="server"> <option value="Application Server">Application Server </option> <option value="Web Server">Rackspace Managed Dedica ...