Hey!!
I wondering how I can make a web page with Arduino and the Ethernet shield there I have a text box to write in, and when I write a specific word I control pins on the Arduino 
I hope someones can help me, because this is something I have wondered about in long time.
Tanks!!!!
I have example server sketches in the playground. It uses text fields. You should be able to modify it to do what you want.
http://playground.arduino.cc/Code/WebServerST
The second example is the smallest as far as memory.
You can also search the forum for zoomkat's server code. His works pretty good.
Simple text box server code.
//zoomkat 12-08-12
//get submit box code
//for use with IDE 1.0
//open serial monitor to see what the arduino receives
//use the \ slash to escape the " in the html or use a '
//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
 //start Ethernet
 Ethernet.begin(mac, ip, gateway, gateway, subnet);
 server.begin();
 //enable serial data print
 Serial.begin(9600);
 Serial.println("server text box test1"); // 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); //see what was captured
     //now output HTML data header
     client.println("HTTP/1.1 200 OK");
     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>HTML form GET example</H1>");
     client.println("<FORM ACTION='/' method=get >"); //uses IP/port of web page
     client.println("Pin 5 'on5' or 'off5': <INPUT TYPE=TEXT NAME='LED' VALUE='' SIZE='25' MAXLENGTH='50'>
");
     client.println("<INPUT TYPE=SUBMIT NAME='submit' VALUE='Change Pin 5!'>");
     client.println("</FORM>");
     client.println("
");
     client.println("</BODY>");
     client.println("</HTML>");
     delay(1);
     //stopping client
     client.stop();
     /////////////////////
     if(readString.indexOf("on5") >0)//checks for on
     {
      digitalWrite(5, HIGH);  // set pin 5 high
      Serial.println("Led On");
     }
     if(readString.indexOf("off5") >0)//checks for off
     {
      digitalWrite(5, LOW);  // set pin 5 low
      Serial.println("Led Off");
     }
     //clearing string for next read
     readString="";
    }
   }
  }
 }
}
Thanks for the help