just to agree with what has been said before: getting your body fat percentage measured will be a way more accurate way of measuring your body weight than the scales. Just remember that big massive body builders might weigh the same as your average blubbing beer gut that's walking down the street, but boy the difference both in health and appearance!
Also, like Crystal's said before, try and swap your machine weights for free weights - but if you're new to these, do get someone who knows about proper lifting (a properly qualified instructor would be nice, although they are becoming a rare breed fast as it seems
) to demonstrate and check you for good form. Compound lifts (those that work the bigger muscles, such as deadlifts, squats, bench) will be more effective than, say, doing calves and triceps exercises. But yeah, post a message in the weightlifting section if you want lots of feedback, as more peeps who are into serious lifting are likely to read it there.
Providing that you follow a proper, healthy diet, gaining and losing weight should be as simple as calorie intake vs. use. So if you want to gain weight you put in more calories than you use, if you want to lose weight you use more calories than you put in. Now it's quite hard to determine from '3 sets of 10-12 reps' how many calories you're burning off. If they're quite light weights, which you haven't upped since the day you've started, you won't be spending many calories.
Doing cardio is very helpful when it comes to losing weight, but can be in the way of building up muscle. So it depends what you want most: getting bigger, with muscle replacing bodyfat (long, hard haul, unless you're committed and/or naturally predisposed to gain muscle easily) or losing weight and looking leaner. I know I was well into working out 6 days a week and training to run a 10k, when someone who does know his stuff, cruelly informed me that, as long as I ran 3 times a week, I shouldn't expect to gain much muscle. Despite desperate attempts to prove him wrong, he was right in the end
That's my 2p's worth anyway. Other than that, welcome to the board!
Malcolms Billy (who is never short of words, you're warned!