In Mobile at the Top 3 line menu when clicked displays menu but it touches the top. So, in order to show it down I had used Header at the Top, like as explained in https://forums.xamarin.com/discussion/35913/listview-header-and-footer
I had used it in .cs like:
BindingContext = IdentityHelper.Users.UserName;
listView.SetBinding (ListView.HeaderProperty, new Binding("."));
Now, it's displaying Logged in User Name at the Top.The only problem is I want to set Background & Textcolor of Header ? How can that be done?