Well, I agree with Barb in part. Focusing on the proteins, veggies, and fruits are best. Also, staying away from refined sugars, processed foods as much as possible. My only exception would be the whole grains.
Eliminating grains from your diet will improve your chances at eliminating fat versus just weight. Also, make sure you are eating appropriate for your size and activity level. If you eat too little your body will actually start holding onto the fat and burn the muscle instead.
Moderate exercise is also a good idea, I agree with Barb again. My only addition to that would be to also begin to lift weights. As a woman you are extremely unlikely to gain anything bulky unless you put enormous effort into it and the more muscle you build the faster your will burn calories and the fat. It's also great for the bones.
If you're going to lose in a healthy manner, it won't be fast; and if it's fast, it won't be healthy.
You need to implement a healthy diet - focus on protein, veggies, fruit, nuts, seeds, etc. Stay away from refined sugar, flour, regular pasta and white rice. Opt for Stevia for sweetener, whole grain breads and pastas and brown rice. Opt for low calorie condiments, such as herbs, spices, mustard, vinegar, lemon juice, etc. Leave off the gravies and cream or cheese sauces.
You have to watch portion sizes, more than anything. There are several websites that will tell you what a portion is; for instance, a serving of meat is about the size of a deck of cards, a serving of veggies (without heavy sauces) can be the size of a baseball, etc.
Make sure you adopt a moderate exercise program, as well. You have to burn more calories than you consume, in order to lose weight. Walking is good; go at a brisk pace, building time/distance as your muscles get stronger. Yoga is also excellent.