Presuming you want to give the user some option to select, you could use the NotesUIWorkspace.OpenFileDialog:
getFile = ws.OpenFileDialog(False, "Truckload Pricing Advisements","Microsoft Excel|*.xls","C:\","Import.xls")
If (Isarray(getFile)) Then
ans$ = Cstr(getFile(0))
Else
ans$ = "Cannot access a file"
End If
ans$ will be the file, if one is selected. OpenFileDialog returns an array if something is selected (and you can set to allow multiple selections) or Empty if not.
Cheers,
Brian