C# coding errors PLEASE HELP!!!,I need some help with these c#sharp errors

So I used this code from this link (http://answers.unity3d.com/questions/577288/particle-system-rendering-behind-sprites.html) to write a script to add my particle effect to a sort layer. I soon got these errors.

1: Assets/ParticleSortLayerScript.cs(16,6): error CS0116: A namespace can only contain types and namespace declarations

2: ArgumentException: Illegal characters in path. System.IO.Path.Combine (System.String path1, System.String path2) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.IO/Path.cs:127)

My code is this below:

 using UnityEngine;
 using System.Collections;
 
 public class ParticleSortLayerScript1 : MonoBehaviour {
 
     // Use this for initialization
     void Start () {
 
         particleSystem.renderer.sortingLayerName = "Fog";
 
     }
 }

Please help me, this is my first time with scripts and making a game in general.

,So I made a script from this question (http://answers.unity3d.com/questions/577288/particle-system-rendering-behind-sprites.html) in order to have this fog particle effect to render in front of other layers. I made a layer in front of the other ones called "fog".

I got these two errors after I made the script for the particle effect.

1: Assets/ParticleSortLayerScript.cs(16,6): error CS0116: A namespace can only contain types and namespace declarations

2: ArgumentException: Illegal characters in path. System.IO.Path.Combine (System.String path1, System.String path2) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.IO/Path.cs:127)

This is my code below:

 using UnityEngine;
 using System.Collections;
 
 public class ParticleSortLayerScript1 : MonoBehaviour {
 
     // Use this for initialization
     void Start () {
 
         particleSystem.renderer.sortingLayerName = "Fog";
 
     }
 }

Please help me! This is my first time making a 2D game on Unity so I'm obviously very new to this.