From arduino Ethernet shiled to Camera stream

i have a project where i need to send some kind of text to the camera stream , which you can access with writing ip adress in the link bar in the browser and you write the password and the username , i am using arduino ethernet shield my code so far is the following .Am i in the right direction , and how to enter the password and the admin characters so that the arduino can access the stream , i am new to all of this. I need samo kind of authentication.

#include <SPI.h>
 #include <Ethernet.h>
String c = "uspeav";
byte mac[]     = { 0x90, 0xA2, 0xDA, 0x0D, 0x83, 0x9D };
byte ip[]      = { 192, 168,   0,  102 }; 
byte gateway[] = { 192, 168,   0,  1 };   
byte subnet[]  = { 255, 255, 255,   0 };   
//String c = uspeav;
void setup()
{
  Ethernet.begin(mac, ip); 
 Serial.begin(9600); 
 delay(1000);
 //String c = uspeav;
}
void loop()
{ 

 EthernetClient client;

IPAddress server(192,168,0,64);

if (client.connected())
{
  Serial.println("connected");
   client.println("PUT <? xml version: '1.0' encoding='utf-8'?><VideoOverlay><normalizedScreenSize><normalizedScreenWidth>704</normalizedScreenWidth><normalizedScreenHeight>576</normalizedScreenHeight></normalizedScreenSize><attribute><transparent>false</transparent><flashing>false</flashing></attribute><fontSize>adaptive</fontSize><frontColorMode>auto</frontColorMode><alignment>customize</alignment><TextOverlayList><TextOverlay><id>1</id><enabled>true</enabled><displayText>" + c + "</displayText><positionX>0</positionX><positionY>480</positionY></TextOverlay></TextOverlayList><DateTimeOverlay><enabled>true</enabled><positionY>544</positionY><positionX>0</positionX><dateStyle>MM-DD-YYYY</dateStyle><timeStyle>24hour</timeStyle><displayWeek>true</displayWeek></DateTimeOverlay><channelNameOverlay><enabled>true</enabled><positionY>64</positionY><positionX>16</positionX></channelNameOverlay></VideoOverlay>");
    client.println("Connection: keep-alive");
   client.println("Authentication: Basic YWRtaW46MTIzNDVxd2VydHk=");
    client.println("Content-Type:   text/plain; charset=UTF-8");
    client.println("Content-Length: 12");
    client.println("{\"on\":false}");
    }
  else
  {
    Serial.println("Connection Failed.");  
   Serial.println();
  }
 delay(5000); 
}

What is the model of camera and what is the protocol used in your web browser?

you wat to know how to create YWRtaW46MTIzNDVxd2VydHk= from login and password?
(it is admin:12345qwerty)

Yeah i managed to do that ,with the password , but now i need to send text to the ip camera , do you have an ide how , the camera is hikvision i am not sure about the model .