Welcome indeed, 9Jan. If you want to post a poem, go to the "forum" page (there's a button to get you there at the upper left of the screen). That will list all the forums the site offers, grouped by category headings. Follow the list down to the category heading "writing," under which you will find the link to a forum called "personal poetry." Click on that link and you will be in the forum. You can start a thread and post your poetry there by clicking on the "post a new thread" link at the upper left of that screen. It sounds complicated, but it's really just a few quick clicks.
You should be aware, though, that some fledgling poets post here because they want merciless criticism in order to improve their work (better we do it for them than the New Yorker). If you don't want that, BE SURE TO SAY SO AT THE TOP OF THE THREAD.
I hope that's helpful. I look forward to seeing your work.