I have a prob

[Patio87]

I am like 2 hours into learning Tk/tcl and I keep getting this error
 first i'll show you the code

import _tkinter
import sys
win = _TK()
button = Button(win, text = "Goodbye", command = sys.exit)
button.pack()
mainloop()

thats the code heres the error

Traceback (most recent call last):
  File "C:/Python21/s", line 3, in ?
    win = _TK()
NameError: name '_TK' is not defined

please help me im still learning python so be easy on the vocabulary thanks