To move an image (shape/sprite), besides 2 variables to store its coordinates (like your jokerX & jokerY),
it's also necessary to store its speed (common labels: spX & spY, mvX & mvY or incX & incY).

Besides storing the amount of pixels an image object moves, its signum (plus or minus) determines its direction!

There are lotsa posts about moving images. Just make a search! 

Thanks, I did this.

1. int speed=2;
         image(joker, jokerX, jokerY);
         if (jokerX<=520 && jokerY==40){
           jokerX+=1*speed;
         }
         if (jokerX==520 && jokerY<=240) {
           jokerY+=1*speed;
         }
           if (jokerY==240 && jokerX<=520) {
              jokerX+=1*-speed;
            }
   
   

You have to change the signum from the "speed" variables themselves, after they collide w/ a wall: