How to add meta tags?

There are several plugins to do this automagically.

https://www.g-loaded.eu/2006/01/05/add-meta-tags-wordpress-plugin/

…is the top hit in Google and has recently been updated by the author. If you want to do this manually, it would involve editing the templates files and hard coding everything.

A search of the forums:
https://www.ads-software.com/search/metatag?forums=1

returned this:
https://www.ads-software.com/support/topic/83196?replies=2

Thanks for this. ??