Reference a newly opened Workbook to run code on it

I know I can open a workbook and have code run in the same workbook if the mapping to the file is pasted into the macro code.

I want to use an open dialogue box to select it.

This code:

Option Explicit
Private Sub CommandButton1_Click()

Dim directory As String, fileName As String, sheet As Worksheet, total As Integer, fd As Office.FileDialog

Set fd = Application.FileDialog(msoFileDialogFilePicker)

With fd

    .AllowMultiSelect = False

    .Title = "Please select the file."

    .Filters.Clear
    .Filters.Add "Excel 2003", "*.xls?"

    If .Show = True Then
        fileName = Dir(.SelectedItems(1))
    End If
End With

Application.ScreenUpdating = False
Application.DisplayAlerts = False

Workbooks.Open (fileName)

For Each sheet In Workbooks(fileName).Worksheets
    total = Workbooks("import-sheets.xlsm").Worksheets.Count
    Workbooks(fileName).Worksheets(sheet.Name).Copy _
    after:=Workbooks("import-sheets.xlsm").Worksheets(total)
Next sheet

Workbooks(fileName).Close

Application.ScreenUpdating = True
Application.DisplayAlerts = True

allows me to select the file through an open dialogue box but then the workbook opens in a new window.