It's not actually the latest version of Wordpress that you need...  you need to install the latest plugin of Steempress (https://wordpress.org/plugins/steempress/).  Here is the Steemit account of the guys who developed the plug in (https://steemit.com/@steempress-io).

Once you've installed the plugin, you'll need to give it your private posting key so that it will post to your Steem account. From all accounts this seems to be pretty secure.  After that you can set it to when you want to post to the Steem blockchain.  It can be in the same instant, or 7 days later after the post payout, or any time in between.

I would caution you though... since Steemit.com ranks fairly highly with Google (as per the Alexa rankings) then Steemit will steal all the link juice from your blog.  What I mean by this is that if someone Googles a phrase or some keywords that your blog has written about, then the Steemit post will rank higher in that Google search than your blog will.  For me that's kind of a deal breaker... 

I should also warn you that the Steempress plugin takes 20% of your post rewards as a beneficiary... however, once they whitelist you they'll also upvote you, pretty much to the same amount they take (but then they get the curation rewards).  I have no problem with this personally, but I thought you should know.