RFID AND ESP8266 SEND UID TO HTML PAGE

Hi folks ! I'm trying to send the UID from a RC522 RFID TAG to an HTML page.
In that moment with my code I can only show the UID on the serial monitor and write a send a text to an HTML page... Moreover I heard about socket (a command to send datas to a server, I don't know what it is it...)

This is my code :

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>

#include <MFRC522.h>

#define RST_PIN  0 // RST-PIN for RC522 - RFID - SPI - Modul GPIO5 
#define SS_PIN  2 // SDA-PIN for RC522 - RFID - SPI - Modul GPIO4 

MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance

//SSID and Password to your ESP Access Point
const char* ssid = "MySSID_ESP8266";
const char* password = "123456789";

ESP8266WebServer server(80); //Server on port 80

//==============================================================
//     This rutine is exicuted when you open its IP in browser
//==============================================================

void handleRoot() 
{
  server.send(200, "text/plain", "dump_byte_array");
}






                 //=============================================
void setup(void) //                   SETUP 
                 //=============================================

{

//===============================================================
//                   SETUP ACCES POINT
//===============================================================
  Serial.begin(115200);    // Initialize serial communications (Serial.begin(9600));
  Serial.println("");
  WiFi.mode(WIFI_AP);           //Only Access point
  WiFi.softAP(ssid, password);  //Start HOTspot removing password will disable security

  IPAddress myIP = WiFi.softAPIP(); //Get IP address
  Serial.print("HotSpt IP:");
  Serial.println(myIP);
 
  server.on("/", handleRoot);      //Which routine to handle at root location

  server.begin();                  //Start server
  Serial.println("HTTP server started");

  
//===============================================================
//                   SETUP MFRC522
//===============================================================
 //Serial.begin(115200);
  SPI.begin();             // Init SPI bus
  mfrc522.PCD_Init();      // Init MFRC522
 
}









                //===============================================
void loop(void) //                      LOOP
                //===============================================

                
{ 

//===============================================================
//                     LOOP ACCES POINT 
//===============================================================

   server.handleClient();//Handle client requests


//==============================================================
//                     LOOP MFRC522
//==============================================================

// Look for new cards
    if ( ! mfrc522.PICC_IsNewCardPresent()) 
        {
          delay(50);
          return;
        }
  // Select one of the cards
    if ( ! mfrc522.PICC_ReadCardSerial()) 
        {
          delay(50);
          return;
        }
  // Show some details of the PICC (that is: the tag/card)
  Serial.print(F("Card UID:"));
  dump_byte_array(mfrc522.uid.uidByte, mfrc522.uid.size);
  Serial.println();
}

// Helper routine to dump a byte array as hex values to Serial
void dump_byte_array(byte *buffer, byte bufferSize) 
  {
    for (byte i = 0; i < bufferSize; i++) 
        {
          Serial.print(buffer[i] < 0x10 ? " 0" : " ");
          Serial.print(buffer[i], HEX);
        }
   }