I need this translated(Js to C#).

I will do it and explain, but first I ask, why do you need this translated if you don't know C#? Heres how to translate:

In C#, you have to include the files you use, which would be the UnityEngine and the basic System.Collections:

 using UnityEngine;
 using System.Collections

In UnityScript, the code is contained within a class behind the scenes, without you actually having to define the class, and in the class must be the name of the file. (at least, in Unity.):

 public class NameOfScript : MonoBehaviour {
 
 }

Variables in C# are statically typed, meaning you have to declare the variable using the type in place of the js var, for example:

 int example;
 string helloWorld = "SUP world";

Functions in C# are stated with a return type (when you return, what type it is, int, float, etc.) when no return type is needed, use void:

 void Update() {
      //stuff
 }

Like js, C# is the same with the adding, subtracting, etc.

 //javascript AND C# the same
 a = a+b;
 b--;
 b *= 11;
 a = ((b*a) + a*a*a);

Using all of what I typed, your code is this:

 using UnityEngine;
 using System.Collections
 
 
 public class NameOfScript : MonoBehaviour {
 
     Transform spawnPoint;
     int speed;
     float nextFire = 0.0f;
     float fireRate = 0.1f;
     int ammo = 150;
     GUIText ammoText;
     AudioSource shotSound;
     Transform wood;
     Transform sand;
     Transform dirt;
     Transform water;
     Transform enemy;
     int range = 100;
 
 
     // Update is called once per frame
     function Update () {
         if(Input.GetKey(KeyCode.Mouse0) && Time.time > nextFire) {
             if(ammo > 0) {
                 Shot();
                 audio.Play();
                 ammo --;
             }
         }
     }
 
     void Shot() {
         nextFire = Time.time + fireRate;
 
         RaycastHit hit; 
         Vector3 fwd = spawnPoint.TransformDirection(Vector3.forward);
 
         Debug.DrawRay(spawnPoint.position, fwd);
 
         if(Physics.Raycast(spawnPoint.position, fwd, out hit, range)) {
             if(hit.collider.tag == "Dirt") {
               Instantiate(dirt, hit.point, Quaternion.FromToRotation(Vector3.forward, hit.normal));
             }
             if(hit.collider.tag == "Sand") {
               Instantiate(sand, hit.point, Quaternion.FromToRotation(Vector3.forward, hit.normal));
             }
             if(hit.collider.tag == "Wood") {
               Instantiate(wood, hit.point, Quaternion.FromToRotation(Vector3.forward, hit.normal));
             }
             if(hit.collider.tag == "Water") {
               Instantiate(water, hit.point, Quaternion.identity);
             }
             if(hit.collider.tag == "Enemy") {
               Instantiate(enemy, hit.point, Quaternion.FromToRotation(Vector3.forward, hit.normal));
             }
         }
 
     }
 
     void OnGUI() {
         ammoText.text = "Ammo: " + ammo.ToString();
     }
 }