
I have been exactly where you are right now. You have made the first step which is realizing you want to take control of it. Unfortunately after I made that decision I didn't do much more and the weight went up and up and up. I have just gotten back out of the 200's and boy does it feel great!
First, find a support network. Sign up for our Summer Biggest Loser here on the WISH board. No pressure, no real competition, just a bunch of really great and supportive men and women here to offer help, advice, inspiration, support, encouragement and friendship.
Then find a plan you can live with. Decide how you think you would be most comfortable trying to change your eating habits. We have a lot of people that love Weight Watchers and the guidance and support it provides. We have others on plans like Nutri System or Jenny Craig. Some are on low or limited carb plans like Atkins or South Beach. And some like to just try to cut their calories and fat themselves. There are some great websites that can help you plan healthy balanced meals with minimal effort. Take a look at sparkpeople.com and fitday.com to start with. Sparkpeople also has great articles to help you get started and along the way.
Make the commitment. Decide today that you WILL change your eating habits and get healthy. What do you have in your life that matters to you? I want to see my children get married and hopefully see my future grandchildren get married. Being at risk for all the health issues that being overweight causes could mean that my seat would be empty at those weddings and I don't want that to happen. I have that in mind as I make the changes I need to make and make decisions about what goes into my mouth.
Set small attainable goals. Yes, I need to lose another 50 pounds but for right now I am focusing on just 10 of them. 10 pounds isn't so hard to lose it? Just a few months of commitment and you will be there. Then it is just another few months to get another 10 off. Doesn't seem so daunting that way, does it?
Plan ahead for the challenges. Make a list of things you enjoy doing or hobbies you have thought about starting. Pick one to have on hand so the next time you are bored you can turn to it instead of food. Figure out what activities you may be doing that you tend to eat during (like TV or sitting at kids activities) and make a list of what else you could do, or what you can eat that is healthy. Replace the chips with cucumber slices and hummus. Replace the sodas with Crystal Lite or water. It is a change, but your health is worth it.
Of course you should always talk to your doctor before starting a diet and exercise program. Tell the dr what plan you want to follow and ask for any advice they can give.
My personal bias is towards the South Beach diet which has really become not a diet in our house, but just the way my whole family eats now. The book is pretty cheap to buy or usually available at the library. You can find a whole lot of books at the library you may want to check out a few and look through them and see if any of them click with you.

You CAN do this!