ProjectPPC/PPC/App.xaml

<Application x:Class="PPC.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:PPC"
             StartupUri="WindowTasks/WindowTasks.xaml">
    <Application.Resources>
        <local:Date_Users x:Key="UserData"
                          ID_role="0" ID_user="1"
                          Login="TestLogin"
                          Password="TestPassword">
            <local:Date_Users.Role>
                <local:Role Name_role="TestRole"/>
            </local:Date_Users.Role>
            <local:Date_Users.Users>
                <local:Users Email="Test@gmail.com"
                             Name="Иван"
                             Patronymic="Иванович"
                             Surname="Иванов"
                             Phone="88005553535"
                             ID_user="1"/>
            </local:Date_Users.Users>
        </local:Date_Users>
    </Application.Resources>
</Application>