Adding Javascript to WP from old site

Hi – I am a newbie here and have very limited knowledge of Javascript, php etc but do have a programming b/ground. I want to use existing code from a page on our existing site http://www.poncesuites.net/reservation/selectroom.php in a page on the site I am developing using WP 3.7.1 http://www.poncesuiteshotel.com/check-availability.
Below is an extract of the code (there are 1000+ lines in total).
I have looked at many posts and sites regarding this but am unsure where to start. Can someone please point me in the right direction!!

<link href="css/styles.css" rel="stylesheet" type="text/css" />
<script src="datetimepicker_css.js"></script>

<!--sa minus date-->
<script type="text/javascript">
	//============ LEAVE PAGE CONFIRMATION ===============
	var stay_flag = true;
	window.onbeforeunload = function (e) {
	  if (stay_flag){
	  var message = "You are about to reserve room/s.",
	  e = e || window.event;
	  // For IE and Firefox
	  if (e) {
		e.returnValue = message;
	  }

	  // For Safari
	  return message;
	}
	};
</script>
<script type="text/javascript">
	// Error checking kept to a minimum for brevity

	function setDifference(frm) {
	var dtElem1 = frm.elements['start'];
	var dtElem2 = frm.elements['end'];
	var resultElem = frm.elements['result'];

// Return if no such element exists
	if(!dtElem1 || !dtElem2 || !resultElem) {
return;
	}

	//assuming that the delimiter for dt time picker is a '/'.
	var x = dtElem1.value;
	var y = dtElem2.value;
	var arr1 = x.split('/');
	var arr2 = y.split('/');

// If any problem with input exists, return with an error msg
if(!arr1 || !arr2 || arr1.length != 3 || arr2.length != 3) {
resultElem.value = "Invalid Input";
return;
	}

var dt1 = new Date();
dt1.setFullYear(arr1[2], arr1[1], arr1[0]);
var dt2 = new Date();
dt2.setFullYear(arr2[2], arr2[1], arr2[0]);

resultElem.value = (dt2.getTime() - dt1.getTime()) / (60 * 60 * 24 * 1000);
}
</script>
<!--sa minus date// <script type="text/javascript"> -->
<!--sa input that accept number only-->
<SCRIPT language=Javascript>
      <!--
      function isNumberKey(evt)
      {
         var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (charCode < 48 || charCode > 57))
            return false;

         return true;
      }
      //-->
</SCRIPT>

<script type="text/javascript">
function GetInternetExplorerVersion()
  // Returns the version of Internet Explorer or a -1 for other browsers.
  {
    var rv = -1;
    if(navigator.appName == 'Microsoft Internet Explorer')
    {
      var ua = navigator.userAgent;
      varre  = newRegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
      if(re.exec(ua) != null)
      rv = parseFloat( RegExp.$1 );
    }
    return rv;
  }
  function functiononLoad()
  {
    var version = GetInternetExplorerVersion()
    if (version <= 7 && version > -1)
    {
      // Code to run in Internet Explorer 7 or earlier.
	  // document.getElementById(para4).innerHTML="";
	  $("#warning_message_for_browser").hide();
    }
  }
  functiononLoad();
</script>

<?php
	$arival = $_POST['start'];
	$departure = $_POST['end'];
	$adults = $_POST['adult'];
	$child = $_POST['child'];

	// $date_para_start= str_split($arival,"/");

	$date_start_day  =substr($arival,0,2);
	$date_start_month=substr($arival,3,2);
	$date_start_year =substr($arival,6,4);

	$date_end_day  =substr($departure,0,2);
	$date_end_month=substr($departure,3,2);
	$date_end_year =substr($departure,6,4);

	$_SESSION['date_started'] = $date_start_day."/".$date_start_month."/".$date_start_year;
	$_SESSION['date_ended'] = $date_end_day."/".$date_end_month."/".$date_end_year;
	$_SESSION['adultNum'] = "";
	$_SESSION['childNum'] = "";
	//Java Variables

	echo "<script type=\"text/javascript\">";

	echo "var date_start_day=". $date_start_day .";";
	echo "var date_start_month=". $date_start_month .";";
	echo "var date_start_year=". $date_start_year .";";

	echo "var date_end_day=". $date_end_day .";";
	echo "var date_end_month=". $date_end_month .";";
	echo "var date_end_year=". $date_end_year .";";

	echo "var original_adultNum=". $adults .";";
	echo "var adultNum=Number(". $adults .");";
	echo "var childNum=Number(". $child .");";

	echo "</script>";

?>