VB programs

I am trying to find a program to view key on an WinXP CD.I found this site (Planet source Code by Snytax)and copied its instructions below. Can anyone explain how to do it since I am new to VB programs.
WinXP Pro SP2, Pentium 4, 1.8GHz computer.

'**************************************
'Windows API/Global Declarations for :Vi
' ew Windows XP CD Key
'**************************************
Option Explicit
Private Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As Long
Private Declare Function RegOpenKey Lib "advapi32.dll" Alias "RegOpenKeyA" (ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Private Declare Function RegQueryValueEx Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, lpData As Any, lpcbData As Long) As Long ' Note that if you declare the lpData parameter as String, you must pass it By Value.
Private Const REG_BINARY = 3
Private Const HKEY_LOCAL_MACHINE = &H80000002
Private Const ERROR_SUCCESS = 0&
'**************************************
' Name: View Windows XP CD Key
' Description:Function: sGetXPCDKey() wi
' ll return the CD Key for Windows XP in t
' he format XXXXX-XXXXX-XXXXX-XXXXX-XXXXX.
'
' By: Snytax
'
'
' Inputs:Nothing.
'
' Returns:Your Windows XP CD Key.
'
'Assumes:None
'
'Side Effects:None
'This code is copyrighted and has limite
' d warranties.
'Please see http://www.Planet-Source-Cod
' e.com/xq/ASP/txtCodeId.57164/lngWId.1/qx
' /vb/scripts/ShowCode.htm
'for details.
'**************************************

'sGetXPCDKey() -
'Returns the Windows XP CD Key if succes
' sful.
'Returns nothing upon failure.
Public Function sGetXPCDKey() As String
'Read the value of:
'HKLM\SOFTWARE\MICROSOFT\Windows NT\Curr
' entVersion\DigitalProductId
Dim bDigitalProductID() As Byte
Dim bProductKey() As Byte
Dim ilByte As Long
Dim lDataLen As Long
Dim hKey As Long
'Open the registry key: HKLM\SOFTWARE\MI
' CROSOFT\Windows NT\CurrentVersion
If RegOpenKey(HKEY_LOCAL_MACHINE, "SOFTWARE\MICROSOFT\Windows NT\CurrentVersion ", hKey) = ERROR_SUCCESS Then
lDataLen = 164
ReDim Preserve bDigitalProductID(lDataLen)
'Read the value of DigitalProductID
If RegQueryValueEx(hKey, "DigitalProductId ", 0&, REG_BINARY, bDigitalProductID(0), lDataLen) = ERROR_SUCCESS Then
'Get the Product Key, 15 bytes long, off
' set by 52 bytes
ReDim Preserve bProductKey(14)
For ilByte = 52 To 66
bProductKey(ilByte - 52) = bDigitalProductID(ilByte)
Next ilByte
Else
'ERROR: Could not read "DigitalProductID
' "
sGetXPCDKey = " "
Exit Function
End If
Else
'ERROR: Could not open "HKLM\SOFTWARE\MI
' CROSOFT\Windows NT\CurrentVersion "
sGetXPCDKey = " "
Exit Function
End If
'Now we are going to 'base24' decode the
' Product Key
Dim bKeyChars(0 To 24) As Byte
'Possible characters in the CD Key:
bKeyChars(0) = Asc( "B ")
bKeyChars(1) = Asc( "C ")
bKeyChars(2) = Asc( "D ")
bKeyChars(3) = Asc( "F ")
bKeyChars(4) = Asc( "G ")
bKeyChars(5) = Asc( "H ")
bKeyChars(6) = Asc( "J ")
bKeyChars(7) = Asc( "K ")
bKeyChars(8) = Asc( "M ")
bKeyChars(9) = Asc( "P ")
bKeyChars(10) = Asc( "Q ")
bKeyChars(11) = Asc( "R ")
bKeyChars(12) = Asc( "T ")
bKeyChars(13) = Asc( "V ")
bKeyChars(14) = Asc( "W ")
bKeyChars(15) = Asc( "X ")
bKeyChars(16) = Asc( "Y ")
bKeyChars(17) = Asc( "2 ")
bKeyChars(18) = Asc( "3 ")
bKeyChars(19) = Asc( "4 ")
bKeyChars(20) = Asc( "6 ")
bKeyChars(21) = Asc( "7 ")
bKeyChars(22) = Asc( "8 ")
bKeyChars(23) = Asc( "9 ")
Dim nCur As Integer
Dim sCDKey As String
Dim ilKeyByte As Long
Dim ilBit As Long
For ilByte = 24 To 0 Step -1
'Step through each character in the CD k
' ey
nCur = 0
For ilKeyByte = 14 To 0 Step -1
'Step through each byte in the Product K
' ey
nCur = nCur * 256 Xor bProductKey(ilKeyByte)
bProductKey(ilKeyByte) = Int(nCur / 24)
nCur = nCur Mod 24
Next ilKeyByte
sCDKey = Chr(bKeyChars(nCur)) & sCDKey
If ilByte Mod 5 = 0 And ilByte <> 0 Then sCDKey = "-" & sCDKey
Next ilByte
sGetXPCDKey = sCDKey
End Function