Hi Cathbro and
Congratulations on your loss so far! How are the new weights working out for you? I read the Strong Women Stay Slim book a while ago too. I really enjoyed her book as well as the Strong Women Stay Strong. The sites that Pat suggested are wonderful for weight training. The day I found Krista's Stumptuous site it was the beginning of a new day for me.
Spend lots of time there and learn as much as you can about form.
In a few weeks you may also be ready to purchase additional dumbbells within the 10, 12, and maybe even 15lb range depending upon how your progress. You may even find that the Dumbell Row may feel a little better with a heavier weight at 20lbs sooner than you think. Our lats are stronger than we think.
Enjoy the journey and keep us updated with your progress.