First, and foremost, until you understand the correct portions for you food, weigh and measure EVRYTHING you eat.
Second, plan every meal and snack ahead of time. Keeping a full day's nutritional requirement in mind and include the foods that will meet the necessary requirements to sustain all the systems in your body. Like your mother always told you, eat your vegetables, drink your milk and opt for fruit over candy for snacks.
Third, log everything you eat. Calculate the total calories everyday.
Fourth, MOVE! Do the things you enjoy doing, just stay active. Exchange some of your couch time for movement. Anything! Walk or run. Play sports. Yard work and gardening. Dance like no one is watching! You chose and do it on a regular basis. Depending on the amount of physical activy you participate in, you can adjust your caloric intake.
Fifth, pay attention to the quantity of food you are now eating. I would hazard a guess that it will be more than you have been. It takes very little meat to meet your requirements for protein and fat but to get the vitamins, minerals and fiber that is required you will be consuming much larger amounts of vegetables, grains, and fruit. Which, coincidentally, are the foods that fill you up, are satisfying and stay will you the longest. This will result in lowering your actual caloric intake, increase the nutritional value of your diet, and still keep you satiated.
Sixth, learn to try new foods that will add to the variety of options as well as add good nutritional value to your menus.
Seventh, now that you are consuming all of the foods you love in the correct proportions, balanced by your activity level, what is to keep you from maintaining that healthy weight?
There is no need to be in a hurry to lose the excess weight. It will begin to drop off steadily. Just keep in mind this is for life and that small changes will make a huge difference. If you really want to see a faster loss, make only a slightly bigger change in both intake and burn of calories but stay within a sustainable range. If your weightloss slows or you hit a plateau, make another change. By the time you reach that magical number that is you healthy weight you will have developed very strong habits of chosing the right foods and eating them in the right proportions.