Hello, this is may fist topic in this forum, english isn't my native language so be patient please... thanks
I'm trying to put on/off the led "L" of my arduino UNO (PIN 13) via LAN in the first approuch and in the future via Internet.
i'm have connected the arduino to an Raspberry pi and a'm using proccesing to control the led via Serial port ttyACM0. Now I would like tu control that led via lan or internet but I haven't any knowledge oh PHP
What can I do??
Thank you very much!! 
If you get an Ethernet shield, then the below code will produce a web page for controlling some arduino pins.
//zoomkat 8-04-12
//simple button GET server code to control servo and arduino pins 5, 6, and 7
//for use with IDE 1.0
//open serial monitor to see what the arduino receives
//use ' instead of " in the html
//address will look like http://192.168.1.102:84 when submited
//for use with W5100 based ethernet shields
///note that the below bug fix may be required
// http://code.google.com/p/arduino/issues/detail?id=605
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //physical mac address
byte ip[] = { 192, 168, 1, 102 }; // ip in lan
byte gateway[] = { 192, 168, 1, 1 }; // internet access via router
byte subnet[] = { 255, 255, 255, 0 }; //subnet mask
EthernetServer server(84); //server port
String readString;
//////////////////////
void setup(){
 pinMode(5, OUTPUT); //pin selected to control
 pinMode(6, OUTPUT); //pin selected to control
 pinMode(7, OUTPUT); //pin selected to control
 pinMode(8, OUTPUT); //pin selected to control
 //start Ethernet
 Ethernet.begin(mac, ip, gateway, gateway, subnet);
 server.begin();
 //enable serial data print
 Serial.begin(9600);
 Serial.println("server multi pin button test 1.0"); // so I can keep track of what is loaded
}
void loop(){
 // Create a client connection
 EthernetClient client = server.available();
 if (client) {
  while (client.connected()) {
   if (client.available()) {
    char c = client.read();
    //read char by char HTTP request
    if (readString.length() < 100) {
     //store characters to string
     readString += c;
     //Serial.print(c);
    }
    //if HTTP request has ended
    if (c == '\n') {
     ///////////////
     Serial.println(readString); //print to serial monitor for debuging
     client.println("HTTP/1.1 200 OK"); //send new page
     client.println("Content-Type: text/html");
     client.println();
     client.println("<HTML>");
     client.println("<HEAD>");
     client.println("<TITLE>Arduino GET test page</TITLE>");
     client.println("</HEAD>");
     client.println("<BODY>");
     client.println("<H1>Zoomkat's simple Arduino button</H1>");
    Â
     // For simple testing, pin 5, 6, 7, and 8 are used in buttons
     // DIY buttons
     client.println("<a href=/?on2 >ON</a>");
     client.println("<a href=/?off3 >OFF</a>");
     client.println(" <a href=/?off357 >ALL OFF</a>
");
     // mousedown buttons
     client.println("<input type=button value=ON onmousedown=location.href='/?on4;'>");
     client.println("<input type=button value=OFF onmousedown=location.href='/?off5;'>");   Â
     client.println(" <input type=button value='ALL OFF' onmousedown=location.href='/?off3579;'>
");Â Â Â Â
        Â
     // mousedown radio buttons
     client.println("<input type=radio onmousedown=location.href='/?on6;'>ON</>");
     client.println("<input type=radio onmousedown=location.href='/?off7;'>OFF</>");
     client.println(" <input type=radio onmousedown=location.href='/?off3579;'>ALL OFF</>
");Â Â
Â
    Â
     // custom buttons
     client.print("<input type=submit value=ON style=width:100px;height:45px onClick=location.href='/?on8;'>");
     client.print("<input type=submit value=OFF style=width:100px;height:45px onClick=location.href='/?off9;'>");
     client.print(" <input type=submit value='ALL OFF' style=width:100px;height:45px onClick=location.href='/?off3579;'>");
     client.println("</BODY>");
     client.println("</HTML>");
     delay(1);
     //stopping client
     client.stop();
     ///////////////////// control arduino pin
     if(readString.indexOf('2') >0)//checks for 2
     {
      digitalWrite(5, HIGH);  // set pin 5 high
      Serial.println("Led 5 On");
     }
     if(readString.indexOf('3') >0)//checks for 3
     {
      digitalWrite(5, LOW);  // set pin 5 low
      Serial.println("Led 5 Off");
     }
    Â
     if(readString.indexOf('4') >0)//checks for 4
     {
      digitalWrite(6, HIGH);  // set pin 6 high
      Serial.println("Led 6 On");
     }
     if(readString.indexOf('5') >0)//checks for 5
     {
      digitalWrite(6, LOW);  // set pin 6 low
      Serial.println("Led 6 Off");
     }
    Â
     if(readString.indexOf('6') >0)//checks for 6
     {
      digitalWrite(7, HIGH);  // set pin 7 high
      Serial.println("Led 7 On");
     }
     if(readString.indexOf('7') >0)//checks for 7
     {
      digitalWrite(7, LOW);  // set pin 7 low
      Serial.println("Led 7 Off");
     } Â
    Â
      if(readString.indexOf('8') >0)//checks for 8
     {
      digitalWrite(8, HIGH);  // set pin 8 high
      Serial.println("Led 8 On");
     }
     if(readString.indexOf('9') >0)//checks for 9
     {
      digitalWrite(8, LOW);  // set pin 8 low
      Serial.println("Led 8 Off");
     }   Â
     Â
     //clearing string for next read
     readString="";
    }
   }
  }
 }
}