polygon non convex

I can’t understand how glubeginpolygon ecc works…pls is there someone that can write me the code with declerations ecc…i tried but i can’t see the polygon…then i have a problem with glTessVertex(tess,v1,v1)

what means v1,v1??? is it a vector or what??
i put simple the coordinates of my poligon there like 100,100 but doesn’t work!!! help me!!
i need to see the code to understand how it works!!
thanks to everyone who writes it!! pls help me…i’m driving me crazy!