SQLite WP8.1 C# error

I tried to work with SQLite with my project, and I found this tutrial and it close to the project idea. Windows Phone 8.1 SQLite: How to Store Data in Database
the code is very simple, I just modify it with my table WritePadFileContent

public WritePadFileContent ReadWritePadFileContent(int writePadFileContentid)
    {
        using (var dbConn = new SQLiteConnection(App.DB_PATH))
        {
            var existingWritePadFileContent = dbConn.Query<WritePadFileContent>("select * from WritePadFileContents where Id =" + writePadFileContentid).FirstOrDefault();
            return existingWritePadFileContent;
        }
    }

The problem is started with

dbConn.Query<WritePadFileContent>("select * from WritePadFileContents where Id =" + writePadFileContentid).FirstOrDefault();

and the error is

Error 4 'WritePad_CSharpSample.Model.WritePadFileContent' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method 'SQLite.SQLiteConnection.Query(string, params object[])' C:\Users\juste 3al faza\Contacts\Documents\WritePad SDK\WritePad_CSharpMetroSample\WritePad_CSharpSample.WindowsPhone\Helpers\DatabaseHelperClass.cs 54 51 WritePad_CSharpSample.WindowsPhone