gotfusion posted al link the other day.

In his tutorial you will find the answers to all your SEO questions.

You mentioned earlier that you imported your site from NOF7 into NOF12.
In NOF12 you can insert your Meta tags in Site View, properties > tab Meta tags.
Or if you are still using NOF7 and you want to change the existing Metas go back to where you inserted them before.
Either the HTML of the masterborder or the layout.