Where is the Dynamic pages SEO Section ?

Hi everyone
Very important issue
How and where can I find the SEO section of each dynamic page I have created , I am not looking for the template page where I have placed my elements ?
Again I have designed an item page which become in the review 20 pages I need the 20 seo section for the 20 pages , because google webmaster tool is telling me you have 20 duplicate meta description!!!

Thank You shlomi

But i have tried to do it , i realised that none of my data fields is connected except got the ID field and title .
How can i connect my data fields to the SEO SECTION ??