for_vika/praktika_2/zapiss.xaml

<Window x:Class="praktika_2.zapiss"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        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"
        xmlns:local="clr-namespace:praktika_2"
        mc:Ignorable="d"
        Title="Учет МЦ: форма" Height="150" Width="450" WindowStartupLocation="CenterScreen">
    <Grid Background="#00BFFF">
        <TextBlock Text="Выбрать категорию:" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="-250 -80 0 0"/>
        <ComboBox Height="20" Width="150" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="20 -80 0 0">
            <TextBlock>Ценная МЦ</TextBlock>
            <TextBlock>Малоценная МЦ</TextBlock>
            <TextBlock>Спецодежда</TextBlock>

        </ComboBox>
        <Button Name="back" Content="Назад" Height="20" Width="50" Margin="350 100 0 0" Click="back_click"/>
    </Grid>
</Window>