How to use progress bar in kivy which displays progress of installation?

I have designed a simple GUI which I have not developed so much but once I will complete I need GUI to display even the progress of application that what is it doing suppose in my exe it has many steps like reading csv, searching input, etc all such steps are to be displayed on screen and even the progress bar with green or blue color to be displayed that will show how much is remaining or completed. Is it possible in Kivy python. This is my code in Kivy GUI:

from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout
from kivy.properties import StringProperty
from kivy.uix.spinner import Spinner
from kivy.app import App


Builder.load_string('''
<MainScreen>:
    GridLayout:      
        orientation: 'vertical'
        cols: 1
        canvas.before:
            Color:
                rgba: 1, 1, 1, 1  
            Rectangle:
                pos: self.pos
                size: self.size
        GridLayout:      
            orientation: 'vertical'
            cols: 2
            Spinner:
                id: first
                text: ' First Number'
                values: ['1','2','3','4','5','6','7','8','9'] 
            Spinner:
                id: second
                text: ' Second Number'
                values: ['1','2','3','4','5','6','7','8','9']       
        Label:
            id: result
            text: ' Result'
            color: 0,0,0,1
        Button:
            id: res
            on_press: root.onPow(first.text,second.text)
            text: 'Progress'
''')

class MainScreen(FloatLayout):
    changet = StringProperty() 
    def __init__(self, **kwargs):          
        super(MainScreen, self).__init__(**kwargs)
    def onPow(self,fir,sec):
        a = 0
        b = 0
        for i in range((10000)):
            print(b)
            self.ids.result.text=str(b*(int(fir)*int(sec)+i))
            b+=1
class TestApp(App):
    def build(self):
        return MainScreen()

if __name__ == "__main__": 
    TestApp().run()     

And when I run this code buttons are of bigger size I need them to be small as per their text or all the butoons of same size. Thank you

Progress bar image

sample image of what I need