Don't worry about pounds because muscle tone is heavier than flub. You may gain weight or plateau but still get smaller and firmer.
Magic formula: Eat healthy food in healthy mounts-heavy on the fresh vegetables and fruit, and Exercise in a consistent way that is strenuous enough to work your cardio and muscles, but not so grueling that you quit and dread doing it.
You do need some muscle training like weights -ask someone at the gym to walk you through the machines- and/or classes that incorporate muscle resistance. This will be what burns fat. Cardio alone (spinning, jogging in treadmill, Zumba) won't do it. You need those cardio things too-whichever ones you like- but you also need strength training, especially if you are over 30. Some classes are really fun and push you to lengths you wouldn't go to yourself.
I'm 43 and in the best shape of my life. i've done every form of work-out under the sun my whole life. Right now my favorites are yoga, Zumba, Bodyattack, Bodycombat, Step, CXWorks core training (all at Gold's but most gyms have comparable options). I do weights and treadmills if I have to. I LOVE long fast walks on cold days more than anything. I change it up so I don't get bored. And most of all: I eat healthy fresh food. 75% raw fresh produce, 25% healthy carbs and protein and a little junk. I take holidays and splurge days, but I'm on track most of the time. I exercise a few times per week at gym for an hour and fit in natural walks, yoga etc whenever I can. Because my diet is good, that's all it takes and I don't gain weight. When my diet is not good I gain weight and have to work out much harder to get it back off.
Be friendly at your gym! I have some really good "gym friends" in certain classes which helps me stay motivated to show up. Learning new exercise techniques is FUN and builds confidence and so does looking good in your clothes!!
Good work getting this going! Do as many different things as you can until you have your favorite things.