How to draw circle use openGL?

How to draw circle use openGL and then the circle move from middle top and down? use c++

Take a look at the Lessons here: http://nehe.gamedev.net/

but that website doesn't have circle movement from top to down sample...

if you can draw a circle, you can easily move it like you move any other object - pushMatrix(), transform / rotate it into the right spot, draw the circle, then popMatrix();

but use what to display? for example squre use glRectf(x,y) how about circle?

You can either do it manually (google "openGL circle" to find code)
*or* a good way is to use quadrics:
http://jerome.jouvie.free.fr/OpenGl/.../Tutorial7.php