Any one please explain this code line by line

    protected void Page_Load(object sender, EventArgs e)
    {
        if(Request.Files.Count != 0)
        {
            HttpPostedFile httpFile = Request.Files[0];
            string extension = this.GetFileExtension(httpFile.ContentType);
            if(extension == null )
            {
                Response.Write("Mime type not Supported");
                return;
            }
            BufferedStream bf = new BufferedStream(httpFile.InputStream);
            byte[] buffer = new byte[bf.Length];
            bf.Read(buffer,0,buffer.Length);
            DataAccess data = new DataAccess();
            data.addImage(buffer,extension);
            Response.Write("Image Added!");
        }
    }

    private string GetFileExtension(string p)
    {
        return p;
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
    }
    
    public class DataAccess
    {
        MySqlConnection con = new MySqlConnection("user id=root; password=admin; database=qms; server=localhost");
        public string addImage(byte[] buffer, string extension)
        {
            string strSql = "SELECT * FROM image";
            DataSet ds = new DataSet("Image");
            MySqlDataAdapter tempAP = new MySqlDataAdapter(strSql, this.con);
            MySqlCommandBuilder objCommand = new MySqlCommandBuilder(tempAP);
            tempAP.Fill(ds, "Table");

            try
            {
                this.con.Open();
                DataRow objNewRow = ds.Tables["Table"].NewRow();
                objNewRow["Extension"] = extension;
                objNewRow["Data"] = buffer;
                ds.Tables["Table"].Rows.Add(objNewRow);
                // trying to update the table to add the image
                tempAP.Update(ds, "Table");
            }
            catch (Exception e) { return e.Message; }
            finally { this.con.Close(); }
            return null;
        }
    }

    protected void Button2_Click(object sender, EventArgs e)
    {
    }

}