what is wrong with this online FPS script(not done) ?

I’m trying to make a online Fps so i look at a toturial on youtube (here is the video)
i have done just the same has him but when i was going to test it when he did (26:00 in the video) i got a error, can someonehelp me?
Here is the script:

using UnityEngine;
using System.collections;
using System. collections.Generic;

public class MultiPlayerManager : MonoBehaviour
{
	public static MultiPlayerManager instance;
	
	public string PlayerName;
		
	private string MatchName = "";	
	private int MatchMaxusers = 32;
	
	public List <MPPlayer> PlayerList = new List<MPPlayer>(); 
		
	void start()
	{
		instance = this;
	}
	
	public void StartServer(string servername,int maxuser)
	{
		MatchName = servername;
		MatchMaxUsers = maxusers;
		Network.InitializeServer(MatchMaxusers, 2550, false);
		Network.InitializeSecurity();	
	}
	
		void OnServerInitialized()
	{
			Server_PlayerJoinRequest("",Network.player);
	}
	
	
	void OnConnectedToServer()
	{
		NetworkView.RPC("PlayerJoinRequest", RPCMode.Server, "", Network,player);
	}
	
	void OnPlayerDisconnected(NetworkPlayer id)
	{
		NetworkView.RPC("Client_RemovePlayer",RPCMode.All, id);
	}
	
	[RPC]
	void Server_PlayerJoinRequest(string playername, NetworkPlayer view)
	{
		NetworkView.RPC("Client_AddPlayerToList",RPCMode.All, playername, view);
	}
	[RPC]
	void Client_AddPlayerToList(string playername, NetworkPlayer view)
	{
		MPPlayer tempplayer = new MPPlayer();
		tempplayer.playername = playername;
		tempplayer.Playernetwork = view;
		PlayerList.Add(templayer);
	}
	[RPC]
	void Client_RemovePlayer(NetworkPlayer view)
	{
		MPPlayer temppl = null;
		foreach(MPPlayer pl in PlayerList)
		{
			if (pl.PlayerNetwork = view)
		{
				temppl = pl;
		}
		if(temppl != null)
		{
			PlayerList.Remove(temppl);	
		}
	}
}
	
	public class MPPlayer
	{
		public string PlayerName="";
		public NetworkPlayer PlayerNetwork;	
	}

that is the scritp, unity says: “assets/Scripts/MultiPlayerManager.cs(2,14): error CS0234: The type or namespace name collections' does not exist in the namespace System’. Are you missing an assembly reference?”

i’m new to making games so i do not know what is wrong here.

The problem is right at the top. You have put,

using UnityEngine;
using System.collections;
using System. collections.Generic;

Change this to

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

The capitalisation is important, as is the removal of the space on the last line.