In your post you should see in the bottom right a black button with EDIT in it. That should do it for you.
I don't know why your using PHP to write out the page or the javascript, but look into heredoc in PHP.
Fast table with the first and last <td> show/hiding the middle row.
Code:
<!DOCTYPE html>
<html>
<head>
<script>
function toggle() {
if( document.getElementById("hidethis").style.display=='none' ){
document.getElementById("hidethis").style.display = '';
}else{
document.getElementById("hidethis").style.display = 'none';
}
}
</script>
</head>
<body>
<table border="1">
<tr>
<td onclick="toggle();">Always visible</td>
<td>Always visible</td>
<td>Always visible</td>
</tr>
<tr id="hidethis">
<td>Hide this</td>
<td>Hide this</td>
<td>Hide this</td>
</tr>
<tr>
<td>Always visible</td>
<td>Always visible</td>
<td onclick="toggle();">Always visible</td>
</tr>
</table>
</body>
</html>