could someone tell me where i went wrong

hi there im trying to generate a floor for my level in a checkered pattern that is expandable by setting the columns and rows that are needed but its not turning out right here is the code:

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class floor : MonoBehaviour
{
	
	
	public GameObject greytile;
	public GameObject blacktile;
	public int colunms;
	public int rows;
	public Transform floorholder;
	private List<Vector3> gridpos = new List<Vector3> ();
	
	void Start ()
	{
		
		initializelist ();
		makefloor ();
	}
	
	void initializelist ()
	{
		gridpos.Clear ();
		
		for (int z = 0; z < colunms; z++) {
			for (int x = 0; x < rows; x++) {
				gridpos.Add (new Vector3 (x, 0, z));
			}
		}
	}
	
	void makefloor ()
	{
		
		for (int z = 0; z < colunms; z++) {
			for (int x = 0; x < rows; x++) {
				if (x % 2 == 0) {
					GameObject GT_Clone = Instantiate (greytile,new Vector3(x,0,z) , Quaternion.identity)as GameObject ;
					GT_Clone.transform.SetParent(floorholder);
				} else {
					GameObject BT_Clone = Instantiate (blacktile,new Vector3(z,0,x), Quaternion.identity)as GameObject ;
					BT_Clone.transform.SetParent(floorholder);
					
				}
				
			}
			}
		}
	}

could someone please tell what im doing wrong and what to change,thank you in advance, P.s im am aware that columns is spelled wrong in the code i will fix that p.p.s i also know about the dot in the first part of makefloor and it hase been changed on my end

this is what it looks like after the changes

http://imageshack.com/a/img905/6392/DkT55T.png

http://imageshack.com/a/img911/3994/tkpZGW.png

Line 37:

Instantiate (greytile, gridpos., Quaternion.identity); // extra dot like you're trying to access a property/field or method

You have left a period in ‘gridpos’, change it to:

Instantiate (greytile, gridpos, Quaternion.identity);

The error is pretty explicit… look at line 39:

Instantiate (greytile, gridpos., Quaternion.identity);

(quite aside from the fact you’ve got a . in there - what’s that doing?)

gridpos is a List<Vector3>() - you define it as such on line 13. You can’t instantiate an object at a List…

use GameObject GT_Clone = Instantiate (greytile, gridpos, Quaternion.identity) as GameObject;
gridpos should be Vector3 value as well…