The example you copied from is using data in the form of an array holding arrays, you are using data in the form of an array holding objects. Objects and arrays are not the same, and because of this they use different syntaxes for accessing data.
If you don't know the variable names, just do a var_dump($blog); within the loop to see them.
The simplest method - access $blog as an object directly:
Try (assuming those variables are correct):
<?php
foreach ($blogs as $blog) {
$id = $blog->id;
$title = $blog->title;
$content = $blog->content;
?>
<h1> <?php echo $title; ?></h1>
<h1> <?php echo $content; ?> </h1>
<?php } ?>
The alternative method - access $blog as an array:
Alternatively, you may be able to turn $blog into an array with get_object_vars (documentation):
<?php
foreach($blogs as &$blog) {
$blog = get_object_vars($blog);
$id = $blog['id'];
$title = $blog['title'];
$content = $blog['content'];
?>
<h1> <?php echo $title; ?></h1>
<h1> <?php echo $content; ?> </h1>
<?php } ?>
It's worth mentioning that this isn't necessarily going to work with nested objects so its viability entirely depends on the structure of your $blog object.
Better than either of the above - Inline PHP Syntax
Having said all that, if you want to use PHP in the most readable way, neither of the above are right. When using PHP intermixed with HTML, it's considered best practice by many to use PHP's alternative syntax, this would reduce your whole code from nine to four lines:
<?php foreach($blogs as $blog): ?>
<h1><?php echo $blog->title; ?></h1>
<p><?php echo $blog->content; ?></p>
<?php endforeach; ?>
Hope this helped.