How do I add meta keywords to my blog?

either copy them into the header.php file of your theme

https://www.ads-software.com/extend/plugins/all-in-one-seo-pack/
or let this plugin handle meta for you

Would this be wp-blog-header.php in the root dir?

Thanks.

I tend to add meta tags in manually using custom fields (https://codex.www.ads-software.com/Custom_Fields). But depending on how confident you are with editing the theme files RVoodoo suggestion is the simplest.

If you wish for them to be the same on all pages you’d need to edit wp-content/themes/active_theme_name/header.php not wp-blog-header.php. Don’t mess with any of the core wordpress files else future updates could break your site.

what is a meta keyword what should i add?

what is a meta keyword what should i add?

The most suitable keywords that describe your content to the searchengines; the phrases you would like to rank for on google,yahoo…

where i can add it please answer