Drawing Graphics

Hi,
I would like to create a panel that draws a representation of a physical device layout that I am measuring data from.
I would like to draw a circle to represent a device unit; if the device is on (say the value of wave0[0]=1), then I would like to fill the circle red, or if it is off then colour it back. I assume at this point that the whole thing could be put in a loop because I have several hundred to do!?
Any help or starters would be great.
Thanks in advance,
Jason.