How much do you know about coding? I’m guessing not so much, which is fine ??
See where it says <img src="<?php echo get_template_directory_uri('template_directory'); ?>/images/pic02.jpg" alt="advert2" />
? That’s the code that displays the image. src="path/to/image.jpg"
is where the image lives. It will take that and display it on the site. To replace the image to what you want, you can upload it using the Media tool inside the WordPress dashboard. Then take the link to the image and paste it into the src quotes.
alt="title"
is what’s displayed if the image is not found. So you usually want to put a simple title or summary of the image. So if you have a picture of a tree, you could put “tree” in the alt quotes.
Hopefully that helps!
EDIT: if you do use the media tool to upload the image, make sure to remove <?php echo get_template_directory_uri('template_directory'); ?>
from the src quotes.