How to rename a file listed on C# windows form listbox

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C#

I am new to C#. I am working on a Windows Form that should do the following;
1- Browse files on local drive
2- allow the user to select files
3- list the selected files in a listBox
4- allow the user to input new file name and when click the rename button it rename the selected file in the listBox.

I am not able to do step 4 as the new text is changed in the listBox but the actual file name is still the same in folder. Please how can i do that... I have listed below the form.cs Thank you

What I have tried:

public partial class everSupportForm : Form
{
    public everSupportForm()
    {
        InitializeComponent();
    }

    private void buttonSelect_Click(object sender, EventArgs e)
    {


        System.IO.Stream myStream;

        var myDialog = new OpenFileDialog();

        myDialog.InitialDirectory = @"c:\";
        myDialog.Filter = "All files (*.*)|*.*|All files (*.*)|*.*";
        //  + "Images (*.BMP;*.JPG;*.GIF)|*.BMP;*.JPG;*.GIF|" //If you want to add filters for browsing only images.
        myDialog.FilterIndex = 1;
        myDialog.RestoreDirectory = true;
        myDialog.Multiselect = true;
        myDialog.Title = "Please Select File(s) to Rename";

        if (myDialog.ShowDialog() == DialogResult.OK)
        {
            foreach (var file in myDialog.FileNames)
            {
               try
                {
                    if ((myStream = myDialog.OpenFile()) != null)
                    {
                        using (myStream)
                        {

                       outputListBox.Items.Add(System.IO.Path.GetFileName(file));

                        }
                    }
                }

                catch (Exception ex)
                {
                 Could not load File specifying the causes 
               MessageBox.Show("Cannot display the File");
                }
            }
        }

    }

    private void buttonExit_Click(object sender, EventArgs e)
    {
        Application.Exit();
    }

    //buttonRemove method to remove a selected item
    private void buttonRemove_Click(object sender, EventArgs e)
    {
        if (outputListBox.SelectedIndex >=0)
        {
            outputListBox.Items.RemoveAt(outputListBox.SelectedIndex);

        } //End of button remove method
    }

    // buttonClear method to clear the listed images ListBox
    private void buttonClear_Click(object sender, EventArgs e)
    {
        outputListBox.Items.Clear();
    } // End of Clear Method

    private void everSupportForm_Load(object sender, EventArgs e)
    {

    }

    private void buttonRename_Click(object sender, EventArgs e)
    {
        if (outputListBox.SelectedIndex >=0)
        {

            outputListBox.Items[outputListBox.SelectedIndex] = newNametextBox.Text;
        }
        else
        {
            MessageBox.Show("There is no Files in the Above list to be Selected", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }
}