Solidity Event

If any body passed the chapter 13 on cryptozombie, can he please elaborate regarding how we will write our final contract in cryptozombies chapter 13?
https://cryptozombies.io/en/lesson/1/chapter/13
It says that
We want an event to let our front-end know every time a new zombie was created, so the app can display it.

Declare an event called NewZombie. It should pass zombieId (a uint), name (a string), and dna (a uint).

Modify the _createZombie function to fire the NewZombie event after adding the new Zombie to our zombies array.

You're going to need the zombie's id. array.push() returns a uint of the new length of the array - and since the first item in an array has index 0, array.push() - 1 will be the index of the zombie we just added. Store the result of zombies.push() - 1 in a uint called id, so you can use this in the NewZombie event in the next line.

Contract.sol
pragma solidity ^0.4.25;

contract ZombieFactory {

   // declare our event here

   uint dnaDigits = 16;
   uint dnaModulus = 10 ** dnaDigits;

   struct Zombie {
   string name;
   uint dna;
   }

   Zombie[] public zombies;

   function _createZombie(string _name, uint _dna) private {
   zombies.push(Zombie(_name, _dna));
   // and fire it here
   }

   function _generateRandomDna(string _str) private view returns (uint) {
   uint rand = uint(keccak256(abi.encodePacked(_str)));
   return rand % dnaModulus;
   }

   function createRandomZombie(string _name) public {
   uint randDna = _generateRandomDna(_name);
   _createZombie(_name, randDna);
   }

}

I am unable to pass this chapter as I write on line 5 (// declare our event here

event NewZombie(_zombieId, _dna, _name);
function add(_zombieId, _dna) public {
uint _name = _zombieId+_dna;

and on line 15, I modify the array like this

Zombie[] public Newzombie;

I then edit and modify function on line 17-18

function _createZombie(string _name, uint _dna) private {
   Newzombie.push(Zombie(_name, _dna));

and on line 19 (// and fire it here

emit _zombieId.Newzombie.push(_name, _dna) -1;
return _name;

but getting the error, can anyone please correct all my mistakes and provide the complete source?

It'll be appreciated if anyone may help

Regards