This is all sound advice by other posters!!!
Just remember, do not try and eat too much, too soon. I know this sounds ludicrous as you need to eat, you've admitted yourself that you're an anorexic, but just hear me out. Do not try and eat a full roast dinner, or go out to a restaurant straight away. Your stomach probably will have shrunk, I know that mine did. My advice is, at first, eat little and often. This way you will always feel full, but not be sick as you are allowing your body to digest the food as it goes along. Then, when you are more comfortable with the idea of food, teach yourself to eat at the specific times of day that other people eat i.e. breakfast, lunch and dinner. It's very important that you get into a routine with it too. Say have a little every hour and a half or whatever, that is how I came out of mine.
To do this, also plan out your meals for the week on a timetable. This might sound very boring, but anorexia is a mental illness too, and you will get your brain/mind used to the idea before you eat it, therefore you are more likely to become comfortable with the idea of eating foods like that. This also allows you to eat a balanced diet, and therefore should not put on vast amounts of weight in the wrong places. Like you will get a big stomach if you just eat fats all of the time, so a balanced diet will prevent this from happening.
I have been through this and therefore I have outlined what I did to get myself out of it. I have been following this plan for over a year now, and am still recovering. I am not all of the way there yet, but I urge you to start it. I'm telling you this, as if you might think that it's going to happen over night, it won't. Just persevere with it; it WILL happen. I think that you have done fabulously well to have admitted that you have a problem, and this is the road to recovery!!