Before you put on weight you were obviously doing a lot of physical exercise that would have allowed you to burn off quite a few extra calories.
Now that you have slowed down your activity you’ll need to look at what you’re eating now and re-evaluate your choices. It might also be that your metabolism is starting to slow down a little, and this often happens with women about your age; therefore while in the past you may have been able to eat larger portions and/or higher fat/calorie foods, you may now need to be a little more careful.
Most people who want to lose weight already know what they should be doing; that is, they are aware of basic fat and calorie content of foods and they know that in order to lose weight they need to burn more energy than they take in. It takes a reduction of approximately 3,500 calories per week to lose half a kilo.
If you don’t know much about nutrition I suggest 5 small meals a day of non-processed healthy foods to start with, but whatever you do needs to be do-able long-term so you need to allow yourself some of the things you like to eat as well. Here is a link to a weight loss calculator to help you work out exactly how many calories you need to reduce to lose weight. This site has also got some great info on fat/calorie content of various foods:http://www.caloriesperhour.com/index_loss.php
If you do know all the basic stuff but find yourself picking when you’re not hungry or eating in response to emotions then you may need to do some work separately on this.
Ultimately as you get older, you do need to be aware of what you’re eating because physical exercise alone, while beneficial, must be combined with health, sensible eating if you want to maintain a healthy weight.