Use TextBox for use text entry text box

	<TextBox Grid.Row="1" Grid.Column="1"  Grid.ColumnSpan="1" x:Name="MyTextBox" Header="My Text Box" Background="White" ></TextBox>

	MyTextBox.Text = "Hi";

Hidden TextBox

You can’t set a text box to not visible and have it still take focus / text entry, but you can achieve the same thing by setting its opacity to 0:

MyTextBox.Opacity = 0;

Options

Wrap text / multiline

TextWrapping="Wrap" 

Read only

IsReadOnly="True"