plotting circle on a xy grid

Hello ,

I have a code in which i have developed a sensor network with hundreds of nodes. THese nodes are scattered on a grid by assigining them random X and Y values. Each node has energy level which decays with time. All i want to do is to represnt each node as a small circle on XY grid and change its color if around a thrshold value.

I have no experience in GUI development. Hope you guys can guide me with this.

Really appreciated and thanking in advance.

SDI