PyQt4 Help

import sys
from PyQt4 import QtCore, QtGui, uic
form_class = uic.loadUiType("main.ui")[0]   # Load the UI & class definition for the main window
b = 0 #values keep track of path
a = 0
#text_edit = QPlainTextEdit() #Determine purpose
class MyWindowClass(QtGui.QMainWindow, form_class):
	def __init__(self, parent=None):
		QtGui.QMainWindow.__init__(self, parent)
		self.setupUi(self)
		self.choicea1.clicked.connect(self.choicea1_clicked) #event handler for button being pushed
		self.choiceb1.clicked.connect(self.choiceb1_clicked)
		self.menuExit.triggered.connect(self.menuExit_selected)
		self.restartBegin.triggered.connect(self.restartBegin_selected)
		#text_edit.setPlainText(text) #Determine purpose

	def menuExit_selected(self):
		self.close()

	def restartBegin_selected(self):
		pass #make it restart somehow

	def choicea1_clicked(self): #defines what happens when the button is pushed
		global a
		a+=1
		mainTextEdit.insertPlainText('a1')
		#x=open('a1.txt', 'r')
		#self.lines = x.readlines()
		#print self.lines
		#text=open('a1.txt').read()
		#text=open('a1.txt').read() #troubleshoot
		#pass #Shift to next part of the story

	def choiceb1_clicked(self):
		global b
		b+=1
		mainTextEdit.insertPlainText('b1')
		#x=open('b1.txt', 'r')
		#self.lines = x.readlines()
		#print self.lines
		#print x
		#pass #Shift to next part of the story


app = QtGui.QApplication(sys.argv)   # PtQt program to show our window
myWindow = MyWindowClass()           # Make an instance of the window class
myWindow.show()                         # Start the program and
app.exec_()                             #   display the GUI window