Quaternian rotation to face Camera

hello all, I have a Camera on a path and I want textured planes (like billboards) to turn an face it

Using the Unity docs I have the foot of the plane facing the camera as it moves
no matter how I try to change the (forward & up) parameters I can’t get the plane up 90degrees to face the Cam.

I have been searching forums and would really like to understand it .

here’s my code:
Thanks

using UnityEngine;
using System.Collections;

public class rotateTowards : MonoBehaviour {
	
	public Transform target;	

void Update() {
		Vector3 relativePos = target.position - transform.position;
		Quaternion rotation = Quaternion.LookRotation(relativePos);
		transform.rotation = rotation;
	}
}

Unity has a Quad primitive game object that you can make by:

  GameObject > Create Other > Quad

A Quad is a two triangle plane with a vertical orientation. I don’t know your game mechanic, but the first thing to do is to create a couple of your graphics on Quads. Then you can have this logic in a script attached to each Quad:

 function Update() {
      transform.rotation = Camera.main.transform.rotation;
 }

Here is an alternate for people often want for billboarding:

function Update() {
    var fwd = Camera.main.transform.forward;
    fwd.y = 0.0;
    transform.rotation = Quaternion.LookRotation(fwd);
}