A circle is what you should be attempting to begin with. Rolling in a straight line is more difficult and should be conquered after you can successfully complete circles. Did you watch the video by chance?
*edit* I see that you did If you have realflight 6.5 I'd love to jump online with you for some extra help.
Understanding the chart is great, but is not a prerequisite to learning rollers. It is just one way of illustrating the timing. The chart helps the super analytical types that want to study a lot. At the end of the day rollers are something you really learn by doing them and the amount of practice time required is significant. Have you tried slowing down the physics on your sim?