my code

Question

I was wondering if someone can look at this and see if there are any problem
class MainClass
{
public static List<string> nomi = new List<string>();
public static List<string> password = new List<string>();
public static bool startup = true;
public static bool logged = false;

public static void Main (string[]args)
{
Start();
}
// Starting loop
public static void Start()
{
string choice;
{

console.WriteLine ("Do you want to login or register");
choice = Console.ReadLine();
switch(choice)
{
case "register":
Register();
break;
case"login":
Login (ref logged, out startup);
break;
default:
Console.WriteLine( "Error, please repeat.");
Console.WriteLIne();
}

}
}//Logged in loop
public static void Run()
{
string app;
while (logged== true)
{
Console.WriteLine ("Choose an app: Calculator, Logout, Exit.");
app = Console.ReadLine();

if (app == "calculator"){
Calc();
}else if (app == "check"){
Check();
}else if (app == "exit"){
Console.WriteLine("Goodbye.");
logged = false;
}else if (app =="logout"){
logged = false;
startup = true;
Console.WriteLine ();
Start();
}else{
Console.WriteLine("Invalid app");
Console.WriteLine();
}
}
}
//Registration and login methods
public static void Register()
{
Console.WriteLine("Choose a Name:");
nomi.Add (Console.Readline());
Console.WriteLine("Choose a password");
password.Add (Console.Readline());
Console.WriteLine();
}
public static bool Login(ref bool logged, out bool startup)
{
string name;
string pwd;

Console.WriteLine ("Write your username");
name = Console.ReadLine();
foreach (string nome in nomi){
if (nome == name){
Console.WriteLine (" Write your Password");
pwd = Console.ReadLine();
foreach (string pword in password){
Console.WriteLine("You are logg