Help with display placement

[Samantha]

I am new to Python and am attempting to write a routine that will display a 
five game selection for a power ball drawing. I think I have the random 
drawing set to work ok, but I want to have the dialog box move in the center 
of my screen. I can't seem to get the code correct to do this. Any help 
would be appreciated.
Thanks,
S
This is the routine I have.
###########################

import random
from Tkinter import *
root = Tk()


frame = Label(root, width=50, height=2, background = 'white', text = 
'PowerBall Numbers')
frame.pack()

def GetNumbers():

    numbers = random.sample(xrange(53), 5)
    numbers.sort()
    numbers[0] = numbers[0] + 1

    numbers[1] = numbers[1] + 1

    numbers[2] = numbers[2] + 1

    numbers[3] = numbers[3] + 1

    numbers[4] = numbers[4] + 1
    powerball = random.sample(xrange(42), 1)
    powerball[0] = powerball[0] + 1

    return numbers, powerball

y = 0
sp1 = sp2 = sp3 = sp4 = sp5 ='   '
w = 0
for x in range(5):
 y = y + 1
 MyNumbers= GetNumbers()
 x = MyNumbers

 num1= str(x[0][0])

 num2 = str(x[0][1])

 num3 = str(x[0][2])

 num4 = str(x[0][3])

 num5 = str(x[0][4])

 pbnum = str(MyNumbers[1][0])

 root.title =('Powerball Numbers')
 w = Label(root, width=50, height=2, background= 'white' ,  text='Game 
'+str(y)+': Numbers: '+num1.zfill(2)+'  '+num2.zfill(2)+'  '+num3.zfill(2)+' 
'+num4.zfill(2)+'  '+num5.zfill(2)+'  '+'PowerBall: '+pbnum.zfill(2))
 w.pack()

root.mainloop()

#####################