You'd need to build a dialogue form in which the user can browse to a folder and enter the file name. First add a little function to a standard module, e.g.
Public Function BrowseFile() As String
Dim strFile As String
With Application.FileDialog(2)
.Title = "Select folder and enter file name"
.InitialFileName = "*.xlxs"
If .Show Then
strFile = .SelectedItems(1)
Else
MsgBox "No file selected", vbInformation
Exit Function
End If
End With
BrowseFile = strFile
End Function
Then with a button in the dialog form call the BrowseFile() function and build the line to call the TransferSpreadsheet method, assigning the BrowseFile function's return value to the FileName argument of the method.