multi-curves visualization

i am new on Opengl, and get confused by the program structure when i want to visualize multi-bezier curves in unique canvas.

you know, there is a example about single Bezier curve visualization.

so which part of the program should i control in order to visualize multi-Bezier curves??

The ctrlpoints array, the glMap1f() in init(), or the glEvalCoord1f()???

Thanks very much!!!