drawing polygons and delete them

hi everyone... i need a huge help!!
i'm doing a game for univ and i must find out a way to draw polygons and delete them so i can see the part of a texture that i have like background.
my whole texture at the beginning is cover, for example with a black square.
then i draw a polygon (any kind of polygon!!!)
and i should see the part of the texture that is under the area of my polygon and so on till to discover complitely the texture....
i don't know how to do this...i created a matrix where i put "1" to define the area of my polygon but don't kow how to go on...
pls help me!!
thanks

Are you in the same class as this guy?
http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=1;t=004583

[mikael_aronsson]

You need to read up on alpha values and blending, google should give you a pretty nice load of websites with information about this.