Try this:

Code:

int a;
int b;

void setup() {
  size(200, 200);
  a=0;
  b=0;
}

void draw()
{
  a=mouseX;
  b=mouseY;
}

void mousePressed() {
  print(a);
  println(","+b);
} 

I came up with a new problem I think I'm learning fast
but here's the problem:
int x1;
int y1;
int x2;
int y2;
int w;
int r;
int g;
int b;
void setup() {
 size(800, 450);
 background(255, 255, 255);
 cursor(CROSS);
 noLoop();
}
void draw() {
stroke(r,g,b);
strokeWeight(w);
fill(r,g,b);
line(x1, y1,x2,y2);
line(-x1+800, y1,-x2+800,y2);
stroke(200);
strokeWeight(0);
line(400,0,400,450);
 }
void mouseDragged() {
 redraw();
 x2=mouseX;
 y2=mouseY;
 x1=pmouseX;
 y1=pmouseY;
 if (mouseButton == RIGHT){
   r=255;
   g=255;
   b=255;
   }
 }
void mousePressed() {
 redraw();
 x2=mouseX;
 y2=mouseY;
 x1=pmouseX;
 y1=pmouseY;
  if (mouseButton == RIGHT){
   r=255;
   g=255;
   b=255;
   }
 }
void keyPressed() {
 if (keyCode == ENTER) {
   saveFrame("screenshot##.png");
 }
 if (keyCode == UP) {
   w=w+1;
   }
 if (keyCode == DOWN) {
   if (w!=0){
   w=w-1;
   }
   }  
}
void mouseReleased(){
   noLoop();
   if (mouseButton == RIGHT){
   r=0;
   g=0;
   b=0;
   }
   }

I wrote acode for like a drawing program
what I want it to do is when I press r button and use right and left keys I want the r value to increase then when I press g and b buttons I wnat it to do this same thing for them. There is another problem though there is a
void mouseReleased(){
   noLoop();
   if (mouseButton == RIGHT){
   r=0;
   g=0;
   b=0;
   }
   }
code which would make all my values back to zero I want to use sth like saveString() and loadString() so that it saves the r g b values I give by increasing or decreasing and when I release the right button it goes back to the saved values.. is it too hard to do I dont know the logic seemed very possible to me but I dnt know how to code it exactly?????