How can i create a triangle between 3 3D points


I have create 3 3D points A (X, Y, Z), B (X, Y, Z) and C (X, Y, Z) and would like to create a color surface (triangle) between these points.
How can i do this?
I have google a lot and can’t finde any sample code or commands to use ;(
It would be grade if anyone give me an hint or advise

thx and cya Thommy