Nice lookin' tool ya got there! :icon_thum If you're just getting started, you might find it easier to start with shorter stock.... although I know it's fun to put a piece of wood on there to show the max capacity. :mrgreen:
If you put a long piece on there like that, and start in the middle like you're doing, you'll find that the wood will vibrate excessively and make you feel like you're doing something wrong. I would suggest a shorter piece (say, 12-14" or so), and start rounding the corners off from the END, not in the middle. Take the first few cuts starting maybe a couple of inches from one end, moving toward the end. Once the end is pretty round, start moving your cuts progressively toward the center (but with the bevel still cutting in the same direction - toward the round end). If you start in the middle and move toward the end, you'll get a catch and tearout a corner.
Once you get used to going from square to round (which will only take a piece or two), then move on to longer pieces so you can work on figuring out how to minimize vibration. For a piece as long and thin as you have pictured, I'd suggest a steady rest.