how to point the positive Y axis of an object to a direction

Hey. I'm trying to figure it out how to point the positive side of a game object to a direction. any help would be appreciated, this is the code that I'm currently using:

 //naming the gameobject
 GameObject zPathHolder = new GameObject(z > 0 ? "+Z Path Holder" : "-Z Path Holder");
 //assigning the parent
 zPathHolder.transform.SetParent(tempGO.transform);
 //calculating the world positioni of the holder
 Vector3 holderPosition = new Vector3(x * 10, y * 10, z * 10 + z * 5f);
 //direction from center of the current block to the holder position
 Vector3 dir = holderPosition - tempGO.transform.position;
 //the rotation of the path holder
 Quaternion holderRotation = Quaternion.LookRotation(dir, zPathHolder.transform.right);
 //assigning the world position
 zPathHolder.transform.position = holderPosition;
 //assigning the rotation
 zPathHolder.transform.rotation = holderRotation;

but it doesn't work as expected, how can I fix it?