How do I add META keywords manually?

[AVBrands]

When I Add meta keywords and descripshion manually to "overall_header" ...like that :

<meta name="resource-type" content="document" />
<meta name="distribution" content="global" />
<meta name="keywords" content=" ... " />
<meta name="description" content=" ... " />

There was no changes in site description on Google search.
Except that I got this General sourse at last:

I have duplicated content. How to fix that?! Where to find right files to solve that problem?!

[rexreo7]

there are various ways to add meta keywords, description, etc.
it all depends on what type of your site is and how this information is called.
foe ex. if yours is a static site than most probably the meta details are in the header part of the same page but if yours is a dynamic page than your meta details are called from some other page saved by any name in includes folder in root domain.
http://www.worldcasinoyellowpages.com