I don't necessarily correlate my training zone with my gears, it all depends on the terrain. I monitor my zones with a heart rate monitor. You can do a search on the forum for those terms and come up with a lot of great info on zones and heart rate training. I hear that newbies, male or female, tend to push too high a gear (whether or not they are actually working hard). Generally you want to keep up a high cadence (anywhere from 80 to 110) to avoid mashing your pedals (and knees), so your new cadence monitor will help with that. Do a search here for cadence and you'll also come up with a lot of great info. I myself don't have a cadence monitor, but I've heard people say that when they ride by cadence in a lower gear they can go faster than trying to mash in the big chainring. Congrats on the new bike! How exciting!

Oh, and you rock for commuting 18.5 miles on a hybrid!