Click menu and open new window

I have used Qt designer to create two different windows, input_window.ui and help_window.ui. Here is the python scripts for showing the input window. In input window, there is a menu bar("About>>Help"). How could it pop up a help_window when "Help" is clicked?

Here is init.py

import sys
from input_window import Ui_MainWindow
from PyQt5.QtWidgets import QMainWindow, QApplication
from help_window import Ui_Help



class MainWindow(QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)
        self.Pophelp.triggered.connect(self.Ui_Help)


    def help_window(self):
        self.window=Ui_Help()
        self.window.show()

if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

Here is the code of Ui_Help

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_Help(object):
    def setupUi(self, Help):
        Help.setObjectName("Help")
        Help.resize(251, 99)
        icon = QtGui.QIcon()
        icon.addPixmap(QtGui.QPixmap("logo.png"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        Help.setWindowIcon(icon)
        self.gridLayoutWidget = QtWidgets.QWidget(Help)
        self.gridLayoutWidget.setGeometry(QtCore.QRect(9, 9, 231, 81))
        self.gridLayoutWidget.setObjectName("gridLayoutWidget")
        self.gridLayout = QtWidgets.QGridLayout(self.gridLayoutWidget)
        self.gridLayout.setContentsMargins(0, 0, 0, 0)
        self.gridLayout.setObjectName("gridLayout")
        self.plainTextEdit = QtWidgets.QPlainTextEdit(self.gridLayoutWidget)
        font = QtGui.QFont()
        font.setFamily("Times New Roman")
        font.setPointSize(10)
        font.setBold(True)
        font.setWeight(75)
        self.plainTextEdit.setFont(font)
        self.plainTextEdit.setFrameShape(QtWidgets.QFrame.WinPanel)
        self.plainTextEdit.setFrameShadow(QtWidgets.QFrame.Sunken)
        self.plainTextEdit.setLineWidth(1)
        self.plainTextEdit.setSizeAdjustPolicy(QtWidgets.QAbstractScrollArea.AdjustIgnored)
        self.plainTextEdit.setReadOnly(True)
        self.plainTextEdit.setObjectName("plainTextEdit")
        self.gridLayout.addWidget(self.plainTextEdit, 0, 0, 1, 1)

        self.retranslateUi(Help)
        QtCore.QMetaObject.connectSlotsByName(Help)