Hi there
I think you need to do some research before you grab those weights

Here are a few good places to start:
Krist Scott Dixon's wonderfully informative site
There are hundreds of book on workout programs. Some of my favorites are:
Body for Life by Bill Phillips
Body for Life for Women by Dr. Pamela Peeke
Bodysculting Bible
Body Sculpting Bible for Women
Brother Iron Sister Steel by Dave Draper.
Another approach is to start with weight training videos. There's another part of the exercise forum devoted to videos- I really don't know which ones to suggest.
I think you are right to reasses your BODY rather than your scale weight at this point. At 5'7", 140 is a very reasonable weight. If you are carrying some muscle, you should look great at that weight! Don't be afraid to push yourself. Those 10 pound weights are probably going to be too heavy right now for some exercises (shoulders) and way too light for others (legs and back). Make sure that you target ALL your muscles- not necessarily during the same session, but don't try to "spot tone".
There are also a lot of weight bearing exercises you can do with virtually no equipment for starters: pushups, lunges, dips...add a stability ball and a few weights and you're pretty much set.
And WOW ! Congratulations on that fantastic weightloss

You must feel like a new person!
Mel