If you want to lift at the gym, I recommend a weight lifting book that illustrates how to do certain exercises. Just about any book by Rachel McLish shows how to perform basic gym strength exercises, as well as the book Body For Life.
If you want to strength train at home, (which I do) there are a lot of great videos out there. For beginners-Getting in Shape with Weights for Dummies is GREAT. I really goes through all of the words like reps, sets, and different muscle names and tells you what it all means. It also stresses proper form for each exercise. All it requires is a chair and hand weights. If you have never weight trained before, I would recommend starting with 2 and 3 pound hand weights, and as the exercises get easier, you can move up to 5, 8, and 10 on certain exercises. Women will get nice definition when they move on to larger weights, but you WILL NOT bulk up like Arnold-women do not have the hormones to do that-so don't worry.
When you advance with home videos-some great ones are by Margaret Richard-her website is at www.bodyelectrictv.com.
What I really like about these these is that they give enough time to change your weights between exercises if you need to-most videos go so fast that you are using the same weights for each body part with no time to switch. The muscles in your body are of different strengths and different sizes, and you will find that you need lighter weights for one exercise, and heavier for another. For instance, I take a lot higher weight on my biceps and triceps (front and back of upper arms) than I do when I work my shoulders. I recommend increasing your weight for a certain exercise when doing the last couple is no longer a struggle-when you aren't feeling the contraction of the muscle any longer and the weights are flying through the air-you need to move up.
Some information that applies to gym or home workouts, is that if you are doing a full body strength routine-working every muscle, then you want to leave a day in between your strength training workouts, so your muscles have time to recover. Some people will wrk out three dys a week, do their strength training, and then their cardio-running, walking, aerobics, etc.-and have a rest day in between. Others do their strength training one day, cardio the next, strength the next, alternating them. You CAN strength train every day if you are not doing a full body workout-say doing upper body one day, then lower body and abs the next-or some other split-but you need to remember not to work the same muscles two days in a row. They need that time to recover.
Good luck with strength training-it is truly wonderful and DOES change the shape of your body. I dance and do yoga...but strength training has really helped give me nicer arms, tighter, rounder shoulders, and a flatter more defined tummy area.