Meta Tags for the Products and Categories are reached via the black biohazard in the listing ...

NOTE: it turns orange when properly setup ...

The other pages are built dynamically for you ...

If you want to customize your meta tags further, you can copy the file:
/includes/modules/meta_tags.php

to your templates and overrides directory:
/includes/modules/your_template_dir/meta_tags.php

and make any other additional changes that you like ...