Having trouble adding offsets to my grid

I would like to add some offsets to my points in my grid but I don’t know how. I made it where it had to generate a grid full of cubes from the center but ever since adding that I am unable to figure out how to implement the offset part, I’m trying to do this in the pic.

Example Pic:
[120022-crap.png*_|120022]

Code:

public class Grid : MonoBehaviour {

    public Vector3[] points;

    public int xSize = 5;
    public int zSize = 5;
    public float offset = 1;
	// Use this for initialization
	void Start () {

        points = new Vector3[zSize * xSize];

        for(int i = 0, z = 0; z < zSize; z++)
        {
            for (int x = 0; x < xSize; x++, i++)
            {
                points *= new Vector3(x - (xSize / 2f), z - (zSize / 2));*

print("There are " + points*);*
}
}

* }*
private void OnDrawGizmos()
{
Gizmos.color = Color.black;
for (int i = 0; i < points.Length; i++)
{
Gizmos.DrawSphere(points*, 0.1f);*
}
}

// Update is called once per frame
void Update () {

* }*
}

_*

isnt it just to multiply by 2?

points _= new Vector3((x - (xSize / 2f))*2, (z - (zSize / 2))*2);_

that should make the offsets twice as large ie 2 units instead of 1