Binary write to adress

Hello. Could someone help me making my tool to write hex to .exe ?

Example i have loading from adress hex converting to ascii and showing to textbox.

for (int i = 0x83B4D0; i <= 0x83B4D5; i++)
           {
               br.BaseStream.Position = i;
               textBox8.Text += br.ReadByte().ToString("X2");

           }
           textBox8.Text = ConvertHex(textBox8.Text);

Now can someone help me to make on button click to save to same adress text from textbox?