Clicking Cancel button on popup,Go back to the before pop up page?

I have created a PopupPage in xamarin forms..
What I have done ===== >> MainPage(There is a -- Button) --> Clicked **--> **PopupPage opens.
I want to do but can't figure out how==============>>** PopupPage( "Cancel" button)** -->Clicked **-->PopupPage closes** and **MainPage **will be shown..

What code should I write in the "Cancel" button's event in PopupPage.Xaml.cs to go back to MainPage?