Script for Turning On Partice Effect Prefab on Collision with other Colliders

As the title says, I need to create a script where you can activate on collision, a prefab particle effect.
I need to be able to choose different particle effects and a location to place it on, so the script needs to allow for an option for me to select prefabs from among my files within the Inspector.
This is what I have so far:

using UnityEngine;
using System.Collections;

public class CollisionStartFX : MonoBehaviour


public float _ParticleEffect;
public float _EffectOnLocation;

void OnCollisionEnter (Collision col)



} doesn’t work for activating or deactivating a gameObject, it even says so and underlines it.