Adding extra content in image header

string filepath = @"C:\temp\abc.bmp";
//read all bytes of image
Byte[] imageData = System.IO.File.ReadAllBytes(filepath);

System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
string name = "abc";
string  id = "IBPL123";

//take name in bytes
byte[] bytes1 = new byte[name.Length * sizeof(char)];
bytes1 = encoding.GetBytes(name);

//take id in bytes
byte[] bytes2 = new byte[id.Length * sizeof(char)];
bytes2 = encoding.GetBytes(id);

//assign length +extra 50 bytes
Byte[] bytes3 = new Byte[imageData.Length +50];

//assign all data into new byte
System.Buffer.BlockCopy(bytes1, 0, bytes3, 0, bytes1.Length);
System.Buffer.BlockCopy(bytes2, 0, bytes3, 25, bytes2.Length);
System.Buffer.BlockCopy(imageData, 0, bytes3, 50, imageData.Length);

class Program
{
    static void Main(string[] args)
    {

        byte[] fileByteArray = File.ReadAllBytes(@"C:Pictures\image.jpg");
        byte[] finalByteArray = new byte[fileByteArray.Length + 50];

        Guid personID = Guid.NewGuid();
        string personSurname = "Gates";
        int cnt = 0;

        foreach (var item in personID.ToByteArray())
        {
            finalByteArray[cnt] = item;
            cnt++;
        }
        foreach (var item in Encoding.ASCII.GetBytes(personSurname))
        {
            finalByteArray[cnt] = item;
            cnt++;
        }

        int imgPositionCnt = 50;
        foreach (var imageByte in fileByteArray)
        {
            finalByteArray[imgPositionCnt] = imageByte;
            imgPositionCnt++;
        }

        GetImage(finalByteArray);
        GetPersonData(finalByteArray);

        Console.ReadLine();
    }

    private static byte[] GetImage(byte[] source)
    {
        byte[] image = new byte[source.Length - 50];
        int cnt = 0;
        for (int i = 50; i < source.Length; i++)
        {
            image[cnt] = source[i];
            cnt++;
        }

        FileStream stream = new FileStream(@"C:\test.jpg", FileMode.Create);
        stream.Write(image, 0, image.Length);
        stream.Close();

        return image;
    }

    private static byte[] GetPersonData(byte[] source)
    {
        byte[] personData = new byte[50];
        for (int i = 0; i < personData.Length; i++)
        {
            personData[i] = source[i];
        }

        return personData;
    }
}