Hi,
to expand on the answer from edubey, you need to determine the meta data you wish to include in your page, this is often mandated by the client or the SEO/design agency. It's a big topic that is constantly changing based on what the search engines/facebook/twitter are currently recommending, so best to get this guidance from SEO experts.
You then need to determine which of these properties can be automatically generated (these can be added to the template and the actual values generated on page rendering) or have to be added manually, these can be added to page/component properties and inputed by the author. For adding alt text to an image, you can do this with the Image Component .
Regards,
Opkar