i fiddle fucked around a bit and found this write up that is pretty damn thurough. happy trading

https://steemit.com/steem/@thecryptofiend/how-to-use-blocktrades-the-fastest-and-easiest-way-to-buy-and-sell-steem-sd-and-my-review-of-the-experience

edit: if you want to send a couple hundred $$$ to my account i will let you know if you are doing it right.