Python Help Please!!!!!

Im creating a program... it stimulates a calculator. When i enter to number in the entry points (e1 and e2) and push the add rectangle it will add it for me

So on a calculator there is an add button so this is mine...

r1 = Rectangle(Point(5,5), Point(20,20))
r1.draw(win)

If i click between those points it will add the too entry numbers i enter... but i have a subtract rectangle too which is

r2 = Rectangle(Point(25,5), Point(45,20))
r2.draw(win)

how do i create a while loop so that I can keep entering numbers until i wanna exit.. which i have a rectangle for exiting too which is..

r5 = Rectangle(Point(80,5), Point(60,60))
r5.draw(win)

I need to display the answer on the calculator...

This is python graphics..

This is all I have so far and im stuck

def main():
#Create graphics window
win = GraphWin("Mathemathics", 400, 400)

#Make the background grey
win.setBackground("gray")

#Set Coordinates
win.setCoords(0, 0, 90, 100)

#Draw first rectangle
r1 = Rectangle(Point(5,5), Point(20,20))
r1.draw(win)

#Clone the first rectangle and move it
r2 = r1.clone()
r2.move(20,0)
r2.draw(win)

#Clone the first rectangle and move it
r3 = r1.clone()
r3.move(40,0)
r3.draw(win)

#Clone the first rectangle and move it
r4 = r1.clone()
r4.move(60,0)
r4.draw(win)

#Clone the first rectangle and move it
r5 = r1.clone()
r5.move(60,20)
r5.draw(win)

#Draw the text at those points
Text(Point(12.5,12.5), "+").draw(win)

Text(Point(32,12.5), "-").draw(win)
Text(Point(52,12), "*").draw(win)
Text(Point(72,12.5), "/").draw(win)
Text(Point(72,32), "Exit").draw(win)

#Draw the text
Text(Point(15,80), "Operand 1:").draw(win)
e1 = Entry(Point(20,75), 8)
e1.setText("0")
e1.draw(win)

#Draw the text
Text(Point(15,60), "Operand 2:").draw(win)
e2 = Entry(Point(20,55), 8)
e2.setText("0")
e2.draw(win)

#Draw the text
Text(Point(50,60), "Answer:").draw(win)

#Draw the text
Text(Point(50,90), "Enter two operands and click operation or exit").draw(win)

#Get mouse hit to close window
win.getMouse()
win.close()
main()

please help...I NEED IT ASAP!!