You need to first put the storage chest into your Mog Safe at your Mog House. Once you do so, you should see it in layout. It's pretty self-explanitory from there. Hope this helped.
How do I make this storage chest actually "store" my stuff? I've tried different methods suggested by players, but I'm still getting the original 50 mog space and 2 storage space... The description of this item is rather misleading. Can anyone help me out?
Currently it only adds one storage slot like all other furniture. On February 26th there will be a patch that adds many things including extra storage and stat bonuses for some furniture. Hold on to it for a week or two and you might even be able to sell it for a nice profit. Hard to say until then.