Question Please help Im new to C#

Pleasw help it says
error CS0234: The type or namespace name 'PostProcessing' does not exist in the namespace 'UnityEngine.Rendering' (are you missing an assembly reference?)

Code (CSharp):

1. using System;
2. using System.Collections;
3. using System.Collections.Generic;
4. using Audio;
5. using TMPro;
6. using UnityEngine;
7. using UnityEngine.Rendering.PostProcessing;
8.  
9. public class Settings : MonoBehaviour {
10.  
11.     public TextMeshProUGUI graphicsText, musicText, sfxText;
12.     public PostProcessLayer ppl;
13.     private bool graphics, music, sfx;
14.  
15.     private void Start() {
16.         graphics = true;
17.     }
18.  
19.     public void ChangeGraphics() {
20.         graphics = !graphics;
21.  
22.         ppl.enabled = graphics;
23.         graphicsText.text = "Graphics - ";
24.         graphicsText.text += graphics ? "Fancy" : "Performance";
25.     }
26.  
27.     public void ChangeMusic() {
28.         bool s = AudioManager.Instance.muteMusic;
29.         if (s) musicText.text = "Music - off";
30.         else musicText.text = "Music - on";
31.     }
32.  
33.     public void ChangeSounds() {
34.         bool s = AudioManager.Instance.muted;
35.         if (s) sfxText.text = "Sounds - off";
36.         else sfxText.text = "Sounds - on";
37.     }
38.  
39. }
40.  

And also it says
error CS0246: The type or namespace name 'PostProcessLayer' could not be found (are you missing a using directive or an assembly reference?)

 

I believe you need to install the Post Processing package from the Package Manager (Window -> Package Manager, make sure "All packages" is selected in the top left, search for "post", select it, click install).

 

Thanks bro u rlly helped me alot