As using JSON and populate the ObservableCollection to DataGrid in WPF application?

Now have a php script that generates JSON from the database. Further, this all must be passed to desktop application written in C#. To display you plan to use a DataGrid and fill it using the ObservableCollection. The question how to do it? Do this for the file itself, or rather of the treatment to the script via GET? Also interested in how to convert a JSON to a DataGrid.
Also interested in the justification of such a decision, planning to create a website to display information and C# app to edit, add, delete.