UsersAuthtorization/AvaloniaApplication4/Views/RegPage.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
			 xmlns:vm="using:AvaloniaApplication4.ViewModels"
			 x:DataType="vm:RegPageVM"
             x:Class="AvaloniaApplication4.RegPage">
	<Grid>
		<StackPanel>
			<TextBlock>Введите имя</TextBlock>
		<TextBox Text="{Binding User.FullName}"></TextBox>
		<TextBlock>Введите логин</TextBlock>
		<TextBox Text="{Binding User.Username}"></TextBox>
		<TextBlock>Введите пароль</TextBlock>
		<TextBox PasswordChar="*" Text="{Binding Password}"></TextBox>
			<Button Command="{Binding AddUser}">Зарегистировать</Button>
		</StackPanel>		
	</Grid>
</UserControl>