If you need to add link, you can do this 2 ways.
1. Use variable with the code that you created, but you need to add value to in in the controller.
in the template /storefront/view/default/template/common/header.tp:
<li><a href="<?php echo $account; ?>"><?php echo $text_account; ?></a></li>
in controller /storefront/controller/common/header.php:
Add:
$this->data['text_account'] = $this->language->get('text_account');
$this->data['account'] = $this->html->getURL('account/account');
2. Add relative portion of URL to the template (lazy way
)
<li><a href="/index.php?rt=account/account">My Account</a></li>
FYI. For blue menu above, you can add link using admin -> menu without any code changes.