import tkinter

def click_btn():
    button['text'] = '點選按鈕了'

root = tkinter.Tk()
root.title('第一個按鈕')
root.geometry('800x600')
button = tkinter.Button(root, text = '請點選按鈕', font = ('Times New Roman', 24), command = click_btn)
button.place(x = 200, y = 100)
root.mainloop()