Problem with Light in OpenGL under windows :(

Hello

I created a B-Spline surface with the OpenGL C++. There is no problem concerning displaying it with mode colors.
The only problem that i have is when i light the surface with a spot the light goes through it as like if it was transparent. In an oder words, would you show how can i make my surface opaque?

Thank you in advance

This is normal, casting shadows must be done “by hand”.
Either through stenctil volumes, or more commonly with shadow depth maps.
Search on these forums, you will see a lot of different ways to do cast shadows, from the simplest to the more evolved.