Mouse interactions and graphics problem

Hi everyone, I'm working on a c# app that show a 3d surface obtained from some interpolating points, I have used OpenGL library wrapped from it's dll. My problem is that I have a 3d perpective view and I want to select the interpolanting points with mouse but the mouse position is given from private void Class_MouseMove(object sender, MouseEventArgs e){...} event handler How can I map X Y coord in X Y Z coords of my view? Thankyou a lot in advance. Mirko(buzzy84)