Create bounded movement

Hello, to everyone. I am new in Unity and I am trying to create a simple game in which the player will fire bullets in the direction of the mouse pointer. My problem is that I can not set bounds for the movement of my player, I checked unity manual for bounds but to be honest I couldn't understand. I have put an if condition in which if the x becomes equal to 90 then the object should be placed at x=89. But it doesn't work. Can you please give a help or hint with this??

Here is my code in C#

**using UnityEngine; using System.Collections; public class player : MonoBehaviour { public float speed = 10.0F; public float rotationSpeed = 100.0F; Vector3 pos = new Vector3(0,0,0);

 // Use this for initialization
 void Start () {
             
 }    
 // Update is called once per frame
 void Update () {
       float translation = Input.GetAxis("Vertical") * speed;
     float rotation = Input.GetAxis("Horizontal") * rotationSpeed;
     translation *= Time.deltaTime;
     rotation *= Time.deltaTime;
     transform.Translate(0, 0, translation);
     transform.Rotate(0, rotation, 0);
     pos = transform.position ;        
         if(f.GetMouseButtonDown(0))    {
         
         Plane zeroPlane = new Plane( Vector3.up, Vector3.zero );
         Ray ray = Camera.main.ScreenPointToRay( Input.mousePosition );
         float distance;
         
         if (zeroPlane.Raycast(ray, out distance))
         {
             Vector3 outputPosition = ray.origin + ray.direction * distance;
          
             GameObject go1 = (GameObject)Instantiate(GameObject.Find("bullet"), pos, Quaternion.identity); 
             
             go1.transform.LookAt(outputPosition);
             go1.rigidbody.AddForce( outputPosition * 10, ForceMode.Impulse);
         }
 }
     
     if (pos.x ==90)
     {
         
         transform.Translate(89,y,z);
         
     }    
     
     
 }**