Thank you for your patience.
This is possible by going through Admin panel > menu > Edit Template
You need to add <meta name="keywords" content="keywords,go,here,....,....."> in the head tag.
This is available on the premium subscription.
Page descriptions are more important which you can already edit in the admin panel.
You might find this article helpful:
googlewebmastercentral.blogspot.com/2009/09/google-does-not-use-keywords-meta-tag.html
Cheers!
