public class BaseClass
{
  public void Method() \\ base-class version.
  {
  }
}
public class SubClass : BaseClass
{
  public void Method() \\ Here's the overload.
 {
 }
}
public class MyClass
{
 public void Test()
 {
  SubClass sb = new SubClass();
  sb.Method();
 }
}

public class SubClass : BaseClass
{
 new public void Method()
 {
 }
}

public class BaseClass
{
  public virtual void Method()
  {
  }
}
 public class SubClass : BaseClass
 {
  public override void Method()
 {
 }
}