How to do an update my TreeView in wpf? - wpf

Question

Good evening.
I started studying the technology - wpf in c#
Now I stopped at the section - work with treeview
I want to add a new node in my treeview in my task.
I have a form and button on this form:
...
<Button Name="btn1" Click="ShowForWriteAdrBookName" Content="TestBtn"/>
...
When you run the program on my form is loaded UserControl, which have treeview:
...
<TreeView Name="treeView1"></TreeView>
...
When I press the
...
<Grid>
<Label Name="Label1" Content="Имя адресной книги:" Margin="0,20,0,0"></Label>
<TextBox Name="TextBox1" Width="200" Height="30" Margin="90,-40,0,0"></TextBox>
<Button Content="Ок" Width="80" Height="30" Margin="0,50,0,0" Click="GetAdrBookName"></Button>
<Button Content="Отмена" Width="80" Height="30" Margin="200,50,0,0" Click="MyExit"></Button>
</Grid>
...
After entering text in the TextBox I click OK. Function is called:
...
public void GetAdrBookName(object sender, RoutedEventArgs e)
{
if (String.Compare(TextBox1.Text.ToString(), "") != 0)
{
adrName = TextBox1.Text.ToString().Trim();
this.Close();
CreateAdrBook(adrName);
}
else
{
...
}
}
...
In this function, I read information from textbox. And then call another function:
...
public void CreateAdrBook(string adrNameFromTextBox1)
{
mylist.Add(adrNameFromTextBox1);
int s = mylist.Count;
TreeView();
}
...
In this function, I add getting information from my textbox to my collection:
...
ObservableCollection<string> mylist = new ObservableCollection<string>()
{
"A",
"B",
"C"
};
...
After I added more information in my collection, I add this information to my TreeView in function:
...
void TreeView()
{
foreach (var drive in mylist)
{
TreeViewItem item = new TreeViewItem();
item.Tag = drive;
item.Header = drive.ToString();
item.Items.Add("*");
treeView1.Items.Add(item);
treeView1.Items.Refresh();
treeView1.UpdateLayout();
}
}
...
Question:
How to do an update my TreeView after adding in this TreeView a new element?
Thank you!