Rigidbody, jumping and gravity help

Hi,

I'm making a small 2d game where you start on a small platform in the center of the screen with 4 other platforms, 1 in each corner. The aim of the game is to collect fruit while avoiding falling rocks.

I need help with a couple things.

1. I need help with adding the jump code.

2. I want to have the rocks fall from the top of the screen slowly then hit a collider that makes them speed up.

This is my current code for moving:

 public int speed = 5;
 
 float moveInput = Input.GetAxis("Horizontal") * Time.deltaTime * speed;
         transform.Translate(moveInput, 0, 0);
         
 //Restrict the x movement between 2 values
 if (transform.position.x <= 1086.0f || transform.position.x >= 1104.0f)
 {
     // Clamp between min -2.5 and max 2.5
     float xPos = Mathf.Clamp(transform.position.x, 1086.0f, 1104.0f);
     transform.position = new Vector3(xPos, transform.position.y,
         transform.position.z);    
 }

Thanks in advance.