I keep my cadence around 90-100. I keep it high because I had some knee issues last year that resulted because I was mashing the pedals (AKA: pedaling at a low cadence), so now I spin (AKA: High cadence- 90 to 100).
Candence is really important, because it tells you when to shift. As a newbie, it wasn't until I figured out cadence, did I learn why/when to shift gears.
Basically, your goal is to keep your cadence steady by shifting up/down through your gears. This really taught me how to use my gears properly and not to waste energy.
Best of luck to you!
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather, to skid in broadside thoroughly used-up, totally worn out, and loudly proclaiming: WOW WHAT A RIDE!!!!"