public interface ICalculate
{
   double Summ(double a, double b);
}

public class Calculator : ICalculate
{
   public double Summ(double a, double b)
   {
      return a + b;
   }
   public Calculator() { }
}

public class Interfacer
{
   public ICalculate calculateController { get; set; }
   public double getSumm(double a, double b)
   {
      return calculateController.Summ(a, b);
   }
   public Interfacer() { }
}

Interfacer i = new Interfacer();
Label1.Text = i.getSumm(double.Parse(TextBox1.Text), double.Parse(TextBox2.Text)).ToString();

<configSections>
   <sectionGroup name="spring">
      <section name="context" type="Spring.Context.Support.WebContextHandler, Spring.Web"/>
      <section name="objects" type="Spring.Context.Support.DefaultSectionHandler, Spring.Core"/>
   </sectionGroup>
</configSections>
<spring>
   <context type="Spring.Context.Support.WebApplicationContext, Spring.Web">
      <resource uri="config://spring/objects"/>
   </context>
   <objects xmlns="http://www.springframework.net">
      <object name="Interfacer" type="Interfacer" >
         <property name="calculateController" ref="Calculator"/>
      </object>
      <object name="Calculator" type="Calculator" />
   </objects>
</spring>
...
<system.webServer>
   <validation validateIntegratedModeConfiguration="false"/>
   <modules>
      <add name="Spring" type="Spring.Context.Support.WebSupportModule, Spring.Web"/>
   </modules>
   <handlers>
      <add name="SpringPageHandler" verb="*" path="*.aspx" type="Spring.Web.Support.PageHandlerFactory, Spring.Web"/>
      <add name="SpringContextMonitor" verb="*" path="ContextMonitor.ashx" type="Spring.Web.Support.ContextMonitor, Spring.Web"/>
   </handlers>
</system.webServer>

var myClassInstance = (myClass)ContextRegistry.GetContext().GetObject("myClass");

<spring>
   <context type="Spring.Context.Support.WebApplicationContext, Spring.Web">
      <resource uri="config://spring/objects"/>
   </context>
   <objects xmlns="http://www.springframework.net">
      <object name="Default" type="Default.aspx" >
         <property name="PageCalculator" ref="Interfacer"/>
      </object>
      <object name="Interfacer" type="Interfacer" >
         <property name="calculateController" ref="Calculator"/>
      </object>
      <object name="Calculator" type="Calculator" />
   </objects>
</spring>

Label1.Text = PageCalculator.getSumm(double.Parse(TextBox1.Text), double.Parse(TextBox2.Text)).ToString();