Convert PHP into ASP.Net

<?php <br mode="hold" /?>session_start();
ob_start();

include("../config.php");
echo $count=$_SESSION['count']-1;
echo "  user name  ".$username=$_SESSION['username'];
echo "  user id  ".$userid=$_SESSION['userid'];
echo "  right  ".$right=$_SESSION['right'];
echo "  wrong  ".$wrong=$_SESSION['wrong'];
echo "  last attend  ".$lastattend=$_SESSION['questionattend'];
echo "  score  ".$score=($right/10)*100;
$result = mysql_query("SELECT * FROM scorecard WHERE register_id='".$userid."'"); 
      $row=mysql_fetch_array($result);
    
     
if($row['register_id']==NULL)
{
echo"  new row inserted    ";
mysql_query("INSERT INTO scorecard(register_id,count,last_attend,right_answer,wrong_answer,score) VALUES('$userid','$count','$lastattend','$right','$wrong','$score') ");
}
else
{
echo "    old row updated   ";
mysql_query(" UPDATE scorecard
SET count='$count', last_attend='$lastattend',right='$right',wrong='$wrong',score='$score'
WHERE register_id='$userid'");
}
   


//session_destroy();
//header("location:../online_test.php");

?>
Signin:
session_start();
include("../config.php");
if($_SESSION['userid']==NULL)
{
header("location:../online_test.php");
}

if(isset($_POST['submit']))
    { 
    echo $username=$_SESSION['username'];
    echo $userid=$_SESSION['userid'];
    $result = mysql_query("SELECT * FROM scorecard WHERE register_id='".$userid."'"); 
      $row=mysql_fetch_array($result);
     $row['register_id'];
     
if($row['register_id']==NULL)
      {
      echo "i am if loop";
      $_SESSION['count']=0;
    $category=$_POST[usercat];
    $_SESSION['category']=$category;
    
     $_SESSION['wrong']=0;
     $_SESSION['right']=0; 
      $result = mysql_query("SELECT * FROM online_category WHERE cat_id='".$category."'"); 
      $row=mysql_fetch_array($result);
      
      $result = mysql_query("SELECT * FROM quiz_edit_1  WHERE cat_id='".$category."' ORDER BY quiz_id"); 
     $rowno=mysql_num_rows ($result);
    
     $row=mysql_fetch_array($result);
    echo $_SESSION['question']=$row['quiz_id'];
      
     }
      else
      {
      echo "  i am else part  ";
      $category=$_POST[usercat];
    echo "  category  ".$_SESSION['category']=$category;
    echo "  count  ".$_SESSION['count']=$row['count'];
    echo "  wrong  ".$_SESSION['wrong']=$row['wrong_answer'];
     echo "  right  ".$_SESSION['right']=$row['right_answer']; 
    echo "  last attended   ".$lastattended=$row['last_attend']; 
    $result = mysql_query("SELECT * FROM quiz_edit_1  WHERE cat_id='".$category."' AND quiz_id='".$lastattended."' ORDER BY quiz_id"); 
     
    
     $row=mysql_fetch_array($result);
    echo $_SESSION['question']=$row['quiz_id'];
     }