code:
import tkinter as tk
from tkinter import messagebox

sigma = tk.Tk()
sigma.title("rdq")
sigma.geometry("400x300")

def login():
    username = eu.get()
    password = pu.get()
    
    if username in ["user001", "user002", "user003", "user444", "user763"] and \
       password in ["12345678", "88888888", "34343434", "stupidor", "gg123123"]:
        messagebox.showinfo("good", "Accept.")
        sigma.destroy()
        open_new_window("Xin chào!", username)

    elif username in ["giraffe", "lucidtry"] and password == "1324576812345678":
        messagebox.showinfo("good", "Hi Admin!")
        sigma.destroy()
        open_new_window("Habari", username)

    else:
        messagebox.showerror("Nah", "Wrong.")

def open_new_window(message, username):
    new_win = tk.Tk()
    new_win.title(f"Hi, {username}")
    new_win.geometry("300x200")
    label = tk.Label(new_win, text=message, font=("Arial", 20))
    label.pack(expand=True)
    new_win.mainloop()


labelu = tk.Label(sigma, text="Username:")
labelu.pack(pady=5)
eu = tk.Entry(sigma)
eu.pack(pady=5)

labelp = tk.Label(sigma, text="Password:")
labelp.pack(pady=5)
pu = tk.Entry(sigma, show="•")
pu.pack(pady=5)

blogin = tk.Button(sigma, text="Login", command=login)
blogin.pack(pady=11)

sigma.mainloop()