1- Create a new solution(Ex- MasterDetailPageEx)
2-Open your file (In my Case “MasterDetailPageExPage”)
3- Change “ContentPage” tag to “MasterDetailPage” as shown in image

4- Now create MasterPage Master and Detail Page as shown in image

5- Then create two forms for Master and Detail section of MasterDetailPage

In my case i’ve created two forms MasterPage.xaml and DetailPage.xaml
6- Now add content on pages
1- MasterPage.xaml

2-DetailPage.xaml

7- Now add references of both pages in your MasterDetailPage

8 - Now set MainPage in App.xml.cs
MainPage = new NavigationPage(new MasterDetailPageExPage());
Screenshot-