PM3 newbie questions

[Dawn]

I am such a newbie I'm about to totally emabrrass myself but here goes.

What should the arcing line look like? During my row it dips at the beginning and the end. What does that mean as far as my stroke? How do I improve? Should I strive for a high arc or low one?

Also, what exactly is the "memory" showing me? I get confused with all the different time lines. Is the very top one showing totals for the entire row?

Thanks,
Dawn