How do I control the block placing?

I made a block placing script with help from you guys, but I don’t know how to place the brick down. Do I have to add tags? Here is my script, there are no compile errors, I have a Dirt prefab, a place point that follows the camera in front of the first person.
Script:
#pragma strict

var DirtPrefab : Transform;
var placePointTransform : Transform;

function Start () {
    placePointTransform = GameObject.Find("PlacePoint").transform;
}


function Update() {
    var Block : Transform = Instantiate( DirtPrefab, placePointTransform.position,

Quaternion.identity ); }

Help

well, it looks like you are using the transform of the object you are assigning in the project editor. Maybe you should use a different Vector3 instead of the prefab’s default transform location? have you checked to confirm the location of the vector 3?