How can I get rid of my big stomach?

I am in my late 40's and in the last 5-6 years I have gained a lot of weight. I weighed 150 lbs 6 years ago. I am a woman 5'9" tall. Now I weigh over 200 lbs. Most of the weight is all in my stomach because I just measured my waist and it's 42 inches! A lot of people think I am pregnant! I have to get rid of this belly. I do try to eat right, I do not eat any poultry or seafood.. When I do eat meat it's usually ground beef only. I do like veggies and some fruits. I see that they sell exercise machines targeted for the stomach, but I am wary of them. My question is: What is the best exercises to get rid of this big stomach? Thanks.