Newbie Question

[solaris_1234]

I am trying to learn Python and I have a few questions.

I have created a Class that is essentially a canvas with a red
background. After creation I want to change the background to green.
However I am having problems doing this. 

Here is my code:

from Tkinter import *

class MyApp:
   def __init__(self, parent):
		self.myParent = parent
		self.myContainer = Frame(parent)
		self.myContainer.pack()

		self.b1 = Canvas(self.myContainer, background="red").grid(row=0,
column=0)

def ChangebgColor(self):
   self(bg="green")


root = Tk()
myapp=MyApp(root) #Everything is fine at this point.

raw_input()

ChangebgColor(myapp.b1) # Error Message at this point

raw_input()



Any help will be greatly appreciated.