How can l tell my bullet to go right, not up. (C#)

Hello, l have a problem with my bullets from my tank. When l hover over my tank with the cursor and press down the left mouse button my bullet goes towards the top of the screen, which is good, but l want the bullet to go towards the right hand side of the screen. Thank you for any help. This is my code so far:

 using UnityEngine;
 using System.Collections;
 
 public class PlayerBullet : MonoBehaviour
 {
     float speed;
 
     void Start()
     {
         speed = 4f;
     }
 
     void Update()
     {
         Vector2 position = transform.position;
 
         position = new Vector2 (position.x, position.y + speed * Time.deltaTime);
 
         transform.position = position;
 
         Vector2 max = Camera.main.ViewportToWorldPoint (new Vector2 (1, 1));
 
         if(transform.position.y > max.y)
         {
             Destroy(gameObject);
         }
     }
 }