Can anyone please tell me how to use the enum ports api?

Public Declare Function EnumPorts Lib "winspool.drv" Alias "EnumPortsA" (ByVal pName As String, ByVal Level As Long, ByVal lpbPorts As Long, ByVal cbBuf As Long, pcbNeeded As Long, pcReturned As Long) As Long

I suck @ api, and I can't get it to work.
thanx.