File this one under painfully obvious. In all the excitement of the Plover release, I had forgotten that the actual description of the qwerty-to-steno layout that Plover uses was buried way back in the archives, and that new people trying to figure out how to position their fingers would most likely be totally lost. Sorry about that! By way of apology, I whipped up a new image that should be a little more helpful, and after I finish posting this I'm going to put it on the Plover FAQ Page as well.
The dark blue letters correspond to the letters of the qwerty keyboard. The light blue letters correspond to the letters on the steno keyboard that they produce when Plover is connected. Basically you move your hands half an inch up so that your left thumb is resting between the C and V keys and your right thumb is resting between the N and M keys. The rest should fall into place. a good test sentence to write when you first start up Plover (not least because even keyboards without n-key rollover often type it correctly) is:
AV A WR DVL RU
in qwerty, which corresponds to
SO S TH WOG HF
in steno, which translates to
So is this working?
in English. Now that you know where to put your fingers, try it out and let me know how it goes!