title: How to go back by using action bar in android
body: <p>I have to get this as a result: </p>
  
  <p><a href="https://i.stack.imgur.com/iJ4GC.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iJ4GC.jpg" alt="Screenshot"></a></p>
  
  <p>Moreover, how do I add colour in the action bar's background?</p>