How to add meta keywords and a site description

[cxk]

I recently built a new site into my forum with SMF portal and i noticed google's description of my site is just text from the main page.  I also feel like my rank has slipped significantly. 

I'm thinking this is where I'd add it, could someone just tell me where I should put it in here?  I'm assuming it should be seperated by commas.

<meta http-equiv="Content-Type" content="text/html; charset=', $context['character_set'], '" />
   <meta name="description" content="', $context['page_title_html_safe'], '" />', !empty($context['meta_keywords']) ? '
   <meta name="keywords" content="' . $context['meta_keywords'] . '" />' : '', '
   <title>', $context['page_title_html_safe'], '</title>';

   // Please don't index these Mr Robot.
   if (!empty($context['robot_no_index']))
      echo '
   <meta name="robots" content="noindex" />';

[TheListener]

Admin > Configuration > features and options

Would be a lot easier.

[cxk]

Admin > Configuration > features and options

Would be a lot easier.

I'm using a custom theme, could that cause the keywords to now be added?  Also, is there any way to change what google shows for the site summery or description?

[TheListener]

You have to include your own keywords otherwise the standard ones will be used.

By standard keywords I mean ones such as simple machines forum, forum, and so on.

Also, is there any way to change what google shows for the site summery or description?

That you will have to ask google.

[Kindred]

any decent theme should include the keywords from the standard location. If it does not, you should take it up with the theme author in the support thread for that theme...