Bueno seria asi...
El Codigo en PHP para Utilizar esa Funcion seria...
<?php
function Suma($num1, $num2){
$resultado=($num1 + $num2);
return $resultado;
}
echo(suma($_GET["num1"], $_GET["num2"]));
?>
y la Funcion en vb para llamar a eso Seria en un Modulo:
Option Explicit
Private Declare Function InternetOpen Lib "wininet" Alias "InternetOpenA" (ByVal sAgent As String, ByVal lAccessType As Long, ByVal sProxyName As String, ByVal sProxyBypass As String, ByVal lFlags As Long) As Long
Private Declare Function InternetCloseHandle Lib "wininet" (ByVal hInet As Long) As Integer
Private Declare Function InternetReadFile Lib "wininet" (ByVal hFile As Long, ByVal sBuffer As String, ByVal lNumBytesToRead As Long, lNumberOfBytesRead As Long) As Integer
Private Declare Function InternetOpenUrl Lib "wininet" Alias "InternetOpenUrlA" (ByVal hInternetSession As Long, ByVal lpszUrl As String, ByVal lpszHeaders As String, ByVal dwHeadersLength As Long, ByVal dwFlags As Long, ByVal dwContext As Long) As Long
Private Const INTERNET_OPEN_TYPE_DIRECT As Long = 1
Private Const INTERNET_OPEN_TYPE_PROXY As Long = 3
Private Const INTERNET_FLAG_RELOAD As Long = &H80000000
'Servidor:
Private Const URLServer = "http://www.tulink.com/tuscrip.php"
Private Function OpenURL(sURL As String) As String
Dim hOpen As Long, hFile As Long, sBuffer As String, Ret As Long, sRead As String
sBuffer = Space(1024)
hOpen = InternetOpen("VB-OpenURL", INTERNET_OPEN_TYPE_DIRECT, vbNullString, vbNullString, 0)
hFile = InternetOpenUrl(hOpen, sURL, vbNullString, ByVal 0&, INTERNET_FLAG_RELOAD, ByVal 0&)
Do
InternetReadFile hFile, sBuffer, 1024, Ret
sRead = sRead & Left(sBuffer, Ret)
If Ret = 0 Then Exit Do
Loop
OpenURL = sRead
InternetCloseHandle hFile
InternetCloseHandle hOpen
End Function
Public Function ExecPHP(Var1 As String, Var2 As String) As String
ExecPHP = OpenURL(URLServer & "?num1=" & Var1 & "&num2=" & Var2)
End Function
y en el Form1
Private Sub Form_Load()
MsgBox ExecPHP(4, 6)
End Sub
esto lo que hace es ni bien ejecutas tu programa envia al servidor la Variable1 (4) y la variable2(6) entonces el Servidor nos retorna 10 que es la suma entre 6 y 4...
Cualquier duda me avisas pero creo que esta mas que claro