Collision detection for player sprite and platforms sprites

I have read some topics here on the Processing forum and watched some videos on YouTube towards collision detection in simple games, however most of them are centred in drawings made on Processing itself, such as circles and platforms. I’m using sprites for player and platforms and I need guidance about the structure of my code once again. In which sections of my code should I place the codes for platforms in order to make it solid for the player jump upon and off them? Where should I place the codes for detection collision for the player sprite?

This is what screen displays:

My code:

//****** Setup section starts here ****** //

PImage background;

// bee character
float charSpeed = 5.5;
float charX = 0;
float charY = 450;
PImage charImage;
PImage bee;// bee
float beeX = 300; 
float beeY = 390;
PImage hi; // hi
float hiX = 400;
float hiY = 300;
PImage ve; // ve
float veX = 200;
float veY = 470;

public void setup() {
  size(600, 800); 
  noFill(); // to adjust the image in the screen properly in fullscreen
  background = loadImage("YellowFlowers.jpg"); 
  background.resize(width, height);   

// load bee 

 charImage = loadImage("bee walk 3.png");
 charImage.resize(200, 200);
//load beehives

bee = loadImage("beehive 1.png");
bee.resize(100, 100);
hi = loadImage("beehive 2.png");
ve = loadImage("beehive 3.png");
ve.resize(100, 100);

 ;/*********** drawing section !***********/

public void draw() {
  image(background, 0, 0); // background image

// beehives platforms

image(bee, beeX, beeY);
image(hi, hiX, hiY);
image(ve, veX, veY);

I applied gravity to my bee sprite and now it can jump. My coding is lacking the collision event to make the bee jump upon the three platforms though.