i usually see a red thread in these discussion areas where we can post deals but I do not see one here????

I think the threads highlighted in red are 'sticky'-purposely made to always sit at the top of the page, guess nobody's made one for this forum yet. I don't think people come to this one much. And I think all book deals go in the book bazaar section, even if they're green themed.

I think that's more in the "Discussion by genre" section of the forums.  This forum is under "Chit Chat".

I don't think environmental (or science or green or similar) has a genre forum yet. You could try drumming people up to request it from TPTB, but I wouldn't do that unless you were going to discuss books and not just deals. 

Since there isn't a genre forum for it, head to the book bazaar.