calling html select tag in C#

hello,
i use CreateUserWizard,  and in <asp:CreateUserWizardStep></asp:CreateUserWizardStep> tag i use 
<select size="1" name="city" id="city_id" runat="server"> <option selected="selected" value="">Please Select your City</option> <option selected="selected" value="">city1</option> <option selected="selected" value="">city2</option> </select> how i can call my <select> tag for get what user selected option?
i find other control in CreateUserWizard such az below code:
TextBox AddressTxt = CreateUserWizard1.CreateUserStep.ContentTemplateContainer.FindControl("AddressTxt") as TextBox;
but i dont know how to access my <select> tag and select ...