unless your paper is published in a journal its not a journal paper. I have had a quick look at the website and it states that "Accepted and presented papers will be published in the IEEE GreenTech 2015 conference proceedings and submitted for inclusion in IEEE Xplore®." The proceedings will likely be a pamphlet that is included in the conference pack to delegates. IEEE Xplore seems to be a digital library with no apparent way to submit articles. It's not a journal, they will charge for access to included articles, however your paper will get a DOI and so you can track its popularity
One other consideration is whether your paper is peer reviewed. I have a conference paper, yet it was not peer reviewed. I am looking to publish most of its contents in a peer-reviewed journal, but I will have to acknowledge that most of the paper was presented at this particular conference. Look at the fine print when submitting papers at a conference. Sometimes you may be able to publish the abstract alone, and then you can submit the paper (with a different abstract) to a peer-reviewed journal.