How to Instantiate a particle system at a certain prefab's position?

So i am working on a game where the player (ball) rolls through the level and collects coins. I want to add a vfx i made using the particle system at the the coins position when it is collected.How do i do that? The game is actually an endless runner type game and the levels are generated as the the player moves forward and each level is actually a pre-made prefab which has obstacles and coins. So how do i add effect on the coins position that was just collected? Here is the code :

using UnityEngine; using System.Collections; using UnityEngine .UI ;

public class ScoreManager : MonoBehaviour {

 private float score = 0.0f;
 private int DifficultyLevel=1;
 private int MaxDifficultyLevel = 20;
 private int ScoreToNextLevel = 2;
 public Text YourScoreText;

 private bool IsInvincible ;

 public Text ScoreText;


 public Animator GameoverAnim;

 public Renderer Ball;
 public Material RedBall;
 public Material YellowBall;

 public GameObject coinfx;

   


 

 // Use this for initialization
 void Start () {

     IsInvincible = false;
 
 }
 
 // Update is called once per frame
 void Update () 
 {

     if (score >= ScoreToNextLevel && IsInvincible ==false)
         LevelUp ();
     score += Time.deltaTime;
     ScoreText.text = ((int)score).ToString (); 

 
 }


 void LevelUp()
 {
     if (DifficultyLevel == MaxDifficultyLevel)
         return;
     ScoreToNextLevel *= 2;
     DifficultyLevel++;
     GetComponent <PlayerController > ().SetSpeed (DifficultyLevel );
 }


 void OnTriggerEnter(Collider trig)
 {
     if (trig.gameObject.tag == "Obstacle" && IsInvincible == false)
     {

         //YouLoseCanvas.SetActive(true);

         //Time.timeScale = 0;


         StartCoroutine(gameover());

     }

     else if (trig.gameObject.tag == "InvincibleCoin")
     {

         StartCoroutine(InvincibilityActivate());
     }

     else if (trig.gameObject.tag == "Coin")
     {

         Instantiate(coinfx, );
     
         score = score + 5;
         ScoreText.text = ((int)score).ToString();
         Destroy(trig.gameObject);


     }



 }

 IEnumerator gameover()
 {


     GameoverAnim.SetTrigger ("GameOver");

     YourScoreText.text = "You Scored : " +((int)score).ToString (); 

     if(PlayerPrefs .GetFloat ("Highscore") < score )
     PlayerPrefs.SetFloat ("Highscore", score);

     yield return new WaitForSeconds (1);

     Time.timeScale = 0;



     Debug.Log("GAME OVER !!");     
 }



  IEnumerator InvincibilityActivate()
 {

     IsInvincible = true;
     Ball.material = RedBall;

     GetComponent <PlayerController > ().SetSpeed (20 );

     yield return new WaitForSeconds (5);

     Ball.material = YellowBall;

     GetComponent <PlayerController > ().SetSpeed (DifficultyLevel );

     IsInvincible = false;

} }