Do I have make my own Point and Vector types to overload them ? Why does this not work ?

namespace System . windows
{
public partial struct Point : IFormattable
{
    public static Point operator * ( Point P , double D )
    {
        Point Po = new Point ( );
        return Po;
    }
}
}

namespace SilverlightApplication36
{
public partial class MainPage : UserControl
{

    public static void ShrinkingRectangle ( WriteableBitmap wBM , int x1 , int y1 , int x2 , int y2 , Color C )
    {
        wBM . DrawRectangle ( x1 , y1 , x2 , y2 , Colors . Red );
        Point Center = Mean ( x1 , y1 , x2 , y2 );
        wBM . SetPixel ( Center , Colors.Blue , 3 );
        Point P1 = new Point ( x1 , y1 );
        Point P2 = new Point ( x1 , y2 );
        Point P3 = new Point ( x1 , y2 );
        Point P4 = new Point ( x2 , y1 );
        const int Steps = 10;
        for ( int i = 0 ; i < Steps ; i++ )
        {
            double iF = (double)(i+1) / (double)Steps;
            double jF = ( 1.0 - iF );
            Point P11 = **P1 * jF;**
        }
    }