" is there a place where there is a list of commands that i can view?"
From the page you point to, click on the Reference link...

There, look at the line() function, it should be enough to make your grid.

like philho said, you can use the line function. instead of drawing a lot of lines. you can use 2 loops to do that.
you could also use 2 nested loops and draw a lot of rects, there are probably different ways of doing this. this is one of them.

1. int stepsX = 10;
   int stepsY = 10;
   
   void setup() {
     size(600,500);
     smooth();
     background(255);
   
   }
   
   void draw() {
     background(255);
   
   
   for(int x=0; x<width; x=x+stepsX) {      
   line(x,0,x,height);
   }
    for(int y=0; y<height; y=y+stepsY) {
   line(0,y,width,y);
    }
   
   
   
   
   }