Help in making an animation - Sunburst

Hi,

I am new to Khan  academy and need a bit of help please. I am stuck on the animations section. I am studying the Intro to Javascript. Please help me or provide a link for the group which can. This is my code:

noStroke();

// the beautiful blue sky
background(82, 222, 240);

var sunSize = 30;

draw = function() {// the starting size for the sun

sunSize= 30 + 30;

// The sun, a little circle on the horizon
fill(255, 204, 0);
ellipse(200, 298, sunSize, sunSize);

// The land, blocking half of the sun
fill(76, 168, 67);
rect(0, 300, 400, 100);

};

var sunSize =30 + 30;

and this is the lesson that I am stuck on: https://www.khanacademy.org/computing/computer-programming/programming/animation-basics/pc/challenge-exploding-sun