Hi,
I am a newbie on PHP and trying out the ajax dynamically from PHP/HTML page.

The scenario I am having is:
I am saving customer data from php/html form directly into MySQL by calling the php file. The files code are:

HTML Code:
<html>
	<head>
		<title>Adding Table Row Dynamically using Javascript</title>
		<script type="text/javascript" href="scripts/utls.js">
		</script>
		<script type="text/javascript">
			function createRequest()
{
	try{
		request=new XMLHttpRequest();
	   }
	catch(tryMS)
	{
		try
		{
			request=new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch(otherMS)
		{
			try
			{
				request=new ActiveXObject("Microsoft.XMLHTTP");	
			}
			catch (failed)
			{
				request=null;
			}
		}
	}
				
	return request;
}
			function addCustomer()
			{
				/*alert('Inside Add Customer Function();');*/
				
				
				if(request.readyState==4)
				{
					if(request.status==200)
					{
						
						if(request.responseText=="okay")
						{
							var table=document.getElementById("customertable");
							var rowCount = table.rows.length;
							var row = table.insertRow(rowCount);
							var cell1 = row.insertCell(0);
							var cell2 = row.insertCell(1);
							var cell3 = row.insertCell(2);
							var cell4 = row.insertCell(3);
							cell1.innerHTML=document.getElementById("cname").value;
							cell2.innerHTML=document.getElementById("add1").value;
							cell3.innerHTML=document.getElementById("add2").value;
							cell4.innerHTML=document.getElementById("city").value;
						}
						else
						{
							alert(request.responseText);
						}
					}
				}
}
			//Function that will create request
			
			function addToDB()
			{
				request=createRequest();
				if(request==null)
				{
					alert("Unable to post data to the database Please try again later");
					return;
				}
				else
				{
					var url="addCustomer.php";
					var requestData="cname=" + 
					escape(document.getElementById("cname").value) + "&add1=" +
					escape(document.getElementById("add1").value) + "&add2="  + 
					escape(document.getElementById("add2").value) + "&city="  +
					escape(document.getElementById("city").value);
					request.onreadystatechange=addCustomer;
					request.open("POST",url,true);
					request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
					request.send(requestData);

				}
			}
		</script>
	</head>
	<body>
		<h1>Customer Data</h1>
		<table name="customertable" id="customertable" border="1px">
			<tr>
				<th>Customer Name</th>
				<th>Address-1</th>
				<th>Address-1</th>
				<th>City</th>

			</tr>
		</table>
		<br/>
		<h1>Enter Customer Details</h1>
		<div style="border:1px solid #dedede; width:400px;padding:10px;">
		<form name="cform" action="addcustomer.php" method="post">
			<label for="cname" style="width:50px;">Customer Name:</label>
			<input type="text" name="cname" id="cname"/><br/>
			<label for="cname" style="width:50px;">Address 1:</label>
			<input type="text" name="add1" id="add1"/><br/>
			<label for="cname" style="width:50px;">Address 2:</label>
			<input type="text" name="add2" id="add2"/><br/>
			<label for="cname" style="width:50px;">City:</label>
			<input type="text" name="city" id="city"/><br/>
			<input type="button" value="Add Customer" onclick="addToDB();">
		</form>
		</div>
	</body>
</html>
The Backend PHP File is:
PHP Code:
<?php
    $cname
=$_REQUEST['cname'];
    
$address1=$_REQUEST['add1'];
    
$address2=$_REQUEST['add2'];
    
$city=$_REQUEST['city'];
    if(isset(
$_POST['cname']) && isset($_POST['add1']) && isset($_POST['add2']) && isset($_POST['city']) )
    {
        
$dbc=mysqli_connect('localhost','root','','city') or die('Error Connecting MySQL');
        
$query="INSERT INTO customer (cname,add1,add2,city) VALUES('$cname','$address1','$address2','$city')";
        
$result=mysqli_query($dbc,$query) or die('Error Inserting Row');
        if(
$result)
        {
            echo 
'okay';
        }
        else
        {
            echo 
'denied in result';
        }
    }
    else
    {
        echo 
'denied in if';
    }
    
mysqli_close($dbc);
?>
The Mysql Table is simple: cust_id(int, autoincrement), cname VARCHAR(40), add1 VARCHAR(40), add2 VARCHAR(40), city VARCHAR(30).

The things I want to know are:
1. How can I change this html into php i.e. is it simple by adding <?php ?> around the code or leave the coding of html as it is and save the file with .php extention.

2. How to manage the sessions in PHP i.e. when I make the AJAX call from javascript function i.e.

request.onreadystatechange=addCustomer;
request.open("POST",url,true);
request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
request.send(requestData);

How the sessions data will be sent is it sent automatically behind the scenes by the browser or I need to send the data manually along with ajax call. I know I need to use session_start() at the start of .php file (The existing HTML File) but the thing is how does the sessions data will be sent and managed Do I need to do this manually or it will be done by browser.

Any help will be highly appreciated.

Thanks
PHPNewBie