Help needed!Input analog sensor value from webserver

Hi! I am currently working on a project using arduino mega with ethernet shield. Currently I am using the tutorial from this link (https://startingelectronics.org/tutorials/arduino/ethernet-shield-web-server-tutorial/SD-card-IO/)

I am now trying to write a program that can send values from the webpage text box and sent it to arduino sketch. Any advice on how to do it? Thanks!

Below is some test code with a web page for sending commands to a servo using a text box.

//zoomkat 6-13-15
//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
//Powering a servo from the arduino usually *DOES NOT WORK*.

#include <SPI.h>
#include <Ethernet.h>
#include <Servo.h> 
Servo myservo;  // create servo object to control a servo 
//int n; //value to write to servo

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, newString;

//////////////////////

void setup(){

  //start Ethernet
  Ethernet.begin(mac, ip, gateway, gateway, subnet);
  server.begin();

  //enable serial data print 
  Serial.begin(9600); 
  myservo.writeMicroseconds(1500); //set initial servo position if desired
  myservo.attach(7, 500, 2500);  //the pin for the servo control, and range if desired
  Serial.println("server text box servo test"); // 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.print(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("Set servo position: <INPUT TYPE=TEXT NAME='LED' VALUE='' SIZE='25' MAXLENGTH='50'>
");

          client.println("<INPUT TYPE=SUBMIT NAME='submit' VALUE='Send servo position'>");

          client.println("</FORM>");

          client.println("
");

          client.println("</BODY>");
          client.println("</HTML>");

          delay(1);
          //stopping client
          client.stop();

          /////////////////////
          if (readString.length() >0) {
            //Serial.println(readString); //prints string to serial port out
            int pos1 = readString.indexOf('=');
            int pos2 = readString.indexOf('&');
            newString = readString.substring(pos1+1, pos2);
            Serial.print("newString is: ");
            Serial.println(newString);
            int n = newString.toInt();
            Serial.print("The value sent is: ");
            Serial.println(n);
            readString=""; //clears variable for new input    
            newString=""; //clears variable for new input
            // auto select appropriate value
            if(n >= 500)
            {
              Serial.print("writing Microseconds: ");
              Serial.println(n);
              myservo.writeMicroseconds(n);
              Serial.println();
            }
            else
            {   
              Serial.print("writing Angle: ");
              Serial.println(n);
              myservo.write(n); 
              Serial.println();
            }
          }           
        }
      }
    }
  }
}

louis0206: I am now trying to write a program that can send values from the webpagetext box and sent it to arduino sketch.

Your title suggests to me that the data in the text box is a sensor value? How did it get into the text box?

I would expect the Arduino to be reading the sensor data and sending it to the web page ?

...R