from tkinter import *

def on_click():
    label['text'] = text.get()

root = Tk(className='hello')
root.minsize(600, 400)

label = Label(root, text="your message")
label.pack()

text = StringVar()
text.set('请输入：')
entry = Entry(root)
entry['textvariable'] = text
entry.pack()

frame = Frame(root)
frame.pack()
Button(frame, text="QUIT", fg="red", command=frame.quit).pack(side=RIGHT)
Button(frame, text="change", fg="blue", command=on_click).pack(side=LEFT)

root.mainloop()