Hi Jane,
You sound like you had enough motivation to right this post

That's a step forward right there. Some people need to be really scared for their lives before they try to lose weight other people just get sick of the way they look or feel etc. Whatever the reason, the best way to lose weight is just to start doing it. I would begin by looking at the diet you currently eat and start seeing what changes you could make that would make it healthier like choosing brown rice over white, whole grain breads and pasta, oatmeal over sugary breakfast cereals, turkey bacon over regular bacon etc. Those usually are fairly easy ways to improve your nutrition. Think about adding more fruit and vegetable and yogurt into your diet if you don't eat a lot of that now. I would switch to roasting, broiling most foods and limit the frying and use healthy oils like canola or olive. Fat free or low fat varieties of cheeses, milk etc are a great way to reduce calorie. Using salsa is a great way to add flavor to eggs, rice etc. I like soy chicken too.
Once you have a healthy diet, be aware of how much a portion really is so you can accurately count how many calories are in that portion. A portion of meat is only 3 ounces which is pretty small similar to the palm of your hand or a deck of cards so if you eat more than that add the extra calories. I have a scale and measuring cups that I use so I know how much I am consuming. That's gets easier too since you get to know the portion sizes fairly quickly.
I would get in the habit of reading food labels too when you shop. When you can avoid dressings, sauces, foods containing partially hydrogenated oils and high fructose corn syrup. They are not healthy for you and there are brands that don't use them. Make sure your whole grains state 100% whole wheat not enriched wheat flour etc.
Once you start eating healthy food and know what a portion is you can start meal planning so that you stay within a calorie limit that you decide is best for you. To lose weight most women generally eat about 1200-1500 a day unless they are extremely active.
I know you have health problems that may limit your mobility so it'll be up to you and your doctor to see if you could try doing some low impact exercise that would help improve your fitness. Walking is a great exercise and suitable for most people needing to lose weight. If that's possible you can start easy and gradually add on a few more minutes etc.
Good Luck