在PHP中分离HTML以避免错误

I've just started to study PHP at university and we've been given 10 exercises to do without any real aid we just have to figure it out for ourselves but I can't figure out how to make this work.

I've got a php page with a html table inside that has 10 boxes, in box 5 I have to make a form that allows you to input a four digit integer number or a four letter string and store it in a variable "$x". A user will put the numbers/letters in a box and click on a button labelled "submit" in order to enter the number/letter into the variable.

I made a form from a tutorial in a blank php page as a test and it worked but when I put it inside the HTML code (which is inside the php) I get this error:

Parse error: syntax error, unexpected T_IF, expecting ',' or ';' in Y:\xampp\htdocs\laboneformtest.php on line 33

Below is the code:

<tr>
<td><b>Rectangle 5: input field four digit integer number or four letter string and
store in variable x</b><br /><br />
"if (isset($_POST['name'])) $name = $_POST['name'];
else $name = "(Not Entered)";

echo "
Your name is: $name<br />
<form method="post" action="formtest.php">
What is your name?
<input type="text" name="name" />
<input type="submit" />
</form>
</td>

I realise the form isn't for variable $x yet I just wanted to get this working before I started on that.

PHP code blocks must be delimited with <?php and ?> (if you've got short_tags turned on, <? will work as well.

There is no such thing as a PHP script - there are only files that have PHP code blocks within them, and <?PHP ?> is how you tell the PHP interpreter where it should start executing instead of just outputting.

<?php 

if (isset($_POST['name'])) {
    $name = $_POST[\"name"\];
} else {
    $name = '(Not Entered)';
}

echo "Your name is: $name<br />";
?>

<form>etc......</form>

<?php
    if( $_POST['name'] && $_POST['name'] != ""){
      $name = urldecode( $_POST['name'] );                
    }else{
      $name = "not set";
    }
?>

<table>
<tr>
 <td>
   <?=$name?>
 </td>
</tr>
</table> 
<form here>