PyQt4 help

[Surak]

Hi guys, having some trouble with PyQt;

Im trying to make a simple encode/decode for ROT-13, its just a lineEdit next to a pushbutton i want it so that when i press the push button it encodes the text inside the line edit, heres what i have so far;

#!/usr/bin/env python
#Gnu GPL malarky

import sys
from PyQt4 import QtCore, QtGui

class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(250, 100)
        self.gridLayout = QtGui.QGridLayout(Form)
        self.gridLayout.setObjectName("gridLayout")
        self.lineEdit = QtGui.QLineEdit(Form)
        self.lineEdit.setObjectName("lineEdit")
        self.gridLayout.addWidget(self.lineEdit, 0, 0, 1, 1)
        self.pushButton = QtGui.QPushButton(Form)
        self.pushButton.setObjectName("pushButton")
        self.gridLayout.addWidget(self.pushButton, 0, 1, 1, 1)

        self.retranslateUi(Form)
        QtCore.QObject.connect(self.pushButton, QtCore.SIGNAL("clicked()"), self.lineEdit.update)
        QtCore.QMetaObject.connectSlotsByName(Form)

    def retranslateUi(self, Form):
        Form.setWindowTitle(QtGui.QApplication.translate("Form", "Encrypter", None, QtGui.QApplication.UnicodeUTF8))
        self.lineEdit.setText(QtGui.QApplication.translate("Form", "ROT-13", None, QtGui.QApplication.UnicodeUTF8))
        self.pushButton.setToolTip(QtGui.QApplication.translate("Form", "Click to encode", None, QtGui.QApplication.UnicodeUTF8))
        self.pushButton.setText(QtGui.QApplication.translate("Form", "Encode", None, QtGui.QApplication.UnicodeUTF8))

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    Form = QtGui.QWidget()
    ui = Ui_Form()
    ui.setupUi(Form)
    Form.show()   
    sys.exit(app.exec_())

Any help? thanks in advance.