my title kinda says what im trying to do. Basically i want my background of a picture, when clicked to bring in the new picture and make it the background. I have so far got the new picture, to load, however, it does not stay as the background, you can only see a glimpse of ti when you press the mouse button.

Thanks alot. Here's my code, if you want to try it out.

PImage bg,a;

int rectX, rectY;      // Position of square button
int circleX, circleY;  // Position of circle button
int rectSize = 50;     // Diameter of rect
int circleSize = 53;   // Diameter of circle
color rectColor, circleColor, baseColor;
color rectHighlight, circleHighlight;
color currentColor;
boolean rectOver = false;
boolean circleOver = false;

void setup()
{
 size(282, 500);
 frameRate(30);
 rectColor = color(0);
 rectHighlight = color(51);
 circleColor = color(255);
 circleHighlight = color(204);
 baseColor = color(102);
 currentColor = baseColor;
 circleX = width/2+circleSize/2+10;
 circleY = height/2;
 rectX = width/2-rectSize-10;
 rectY = height/2-rectSize/2;
 ellipseMode(CENTER);
 bg = loadImage("me.jpg");
 a = loadImage("paul 2.jpg");
}

void draw()
{
 background(bg);
 update(mouseX, mouseY);

 if(rectOver) {
   fill(rectHighlight);
 } else {
   fill(rectColor);
 }
 stroke(255);
 rect(rectX, rectY, rectSize, rectSize);
 
 if(circleOver) {
   fill(circleHighlight);
 } else {
   fill(circleColor);
 }
 stroke(0);
 ellipse(circleX, circleY, circleSize, circleSize);
}
void mousePressed(){
  image(a,0,0);
}

void update(int x, int y)
{
 if( overCircle(circleX, circleY, circleSize) ) {
   circleOver = true;
   rectOver = false;
 } else if ( overRect(rectX, rectY, rectSize, rectSize) ) {
   rectOver = true;
   circleOver = false;
 } else {
   circleOver = rectOver = false;
 }
}

boolean overRect(int x, int y, int width, int height)
{
 if (mouseX >= x && mouseX <= x+width &&
     mouseY >= y && mouseY <= y+height) {
   return true;
 } else {
   return false;
 }
}

boolean overCircle(int x, int y, int diameter)
{
 float disX = x - mouseX;
 float disY = y - mouseY;
 if(sqrt(sq(disX) + sq(disY)) < diameter/2 ) {
   return true;
 } else {
   return false;
 }
}

ok thanks, but when i click on the rectangle i get a message saying nullPointerException. do i use the term imageBackground, or is that representing something?

thanks again for the help

ok thats great thanks, but what if i wanted multiple backgrounds, from clicking on the rectangle to get the third picture, then fourth and so on.

Basically im creating a simple game where you click on the rectangle to take to you to a different area of a house and you have to get through it.

would the last post you made have to look like this?

void mousePressed()
{
 if (rectOver){
   ( bg == a ) bg = b;
  if (rectOver){
    ( bg == b ) bg = a;
}
}

ok thanks alot for your help.