Object Manipulation and Frames

[uo]

Hello people,
  I would like to get some advice on the method that i should use to
develop a cyber billing wxpython app.I had started but i hit a snag
when i realised i could not launch or fiddle with properties of a
Frame object within another frame object, what i had intended to do
was to first launch a login frame where members would login and after
successful authentication , the frame would be hidden and another
would be launched for billing...i had a LoginFrame and a BillingFrame
but after successful auth i found it hard to switch the
BillingFrame.Show(True), can this be done  ...and would making use of
MDI make it beter? ...and if not could anyone  please suggest a
better/
workable alternative..Thank you.