As soon as I saw your profile name I knew you had to be from Buffalo. Welcome to Deckbox fellow Buffalonian.
Its pretty straight forward with how your go about trades, just find someone who has what your looking for and propose something. Whenever you actually propose a trade, not just create one, it sends a notice to that persons email. It only helps to say something in the chat box since that tells people your actually human and not some random dude.
Your should also look into joining the Reddit MTG Trades. Its one the most active trading groups. There is also a reddit sub thread every week too. You should check it out.