4 C# errors Endless Runner

 Hy I got 4 Errors and I can't find the problem I'm new and following this tutorial: https://www.youtube.com/watch?v=YOLpjdcBtpA 

These are the errors I hope someone can help me: Assets/scripts/Platformgenerator.cs(22,37): error CS1061: Type UnityEngine.GameObject[]' does not contain a definition for GetComponent' and no extension method GetComponent' of type UnityEngine.GameObject[]' could be found (are you missing a using directive or an assembly reference?)

Assets/scripts/Platformgenerator.cs(34,62): error CS1061: Type UnityEngine.GameObject' does not contain a definition for Length' and no extension method Length' of type UnityEngine.GameObject' could be found (are you missing a using directive or an assembly reference?)

Assets/scripts/Platformgenerator.cs(34,39): error CS1502: The best overloaded method match for UnityEngine.Random.Range(float, float)' has some invalid arguments Assets/scripts/Platformgenerator.cs(34,39): error CS1503: Argument #2' cannot convert object' expression to type float'

The script:

 using UnityEngine;
 using System.Collections;
 
 public class Platformgenerator : MonoBehaviour {
 
     public GameObject[] thePlatform;
     public Transform generationPoint;
     public float distanceBetween;
 
     private float platformWidth;
 
     public float distanceBetweenMin;
     public float distanceBetweenMax;
 
     public GameObject thePlatforms;
     private int platformSelector;
 
     //public Objectpooler theObjectpool;
 
     // Use this for initialization
     void Start () {
         platformWidth = thePlatform.GetComponent<BoxCollider2D> ().size.x;
     }
     
     // Update is called once per frame
     void Update () {
     
         if(transform.position.x < generationPoint.position.x)
         {
             distanceBetween = Random.Range(distanceBetweenMin, distanceBetweenMax);
             
             transform.position = new Vector3(transform.position.x + platformWidth + distanceBetween, transform.position.y, transform.position.z);
 
             platformSelector = Random.Range (0, thePlatforms.Length);
 
             Instantiate (thePlatforms, transform.position, transform.rotation);
 
 
             /*GameObject newPlatform = theObjectpool.GetpooledObject();
 
             newPlatform.transform.position = transform.position;
             newPlatform.transform.rotation = transform.rotation;
             newPlatform.SetActive (true); */
             
         }
     }
 }