This is excellent advice. It is not easy to adjust old habits, but in the end, your heart will thank you. The rest of your body will too because it will benifit all systems to eat healthy.
The most important thing is to limit your sodium...I would have thought the docs would have let you know that....you should definitely keep your sodium intake below 2000 mg per DAY. 1500 would be better. Start reading labels. Most pre-packaged food has horrendous amounts of sodium...example, look at a can of soup and see how many mg of sodium are in it per serving and then look at how many servings are in the can...Your best bet is to buy fresh veggies or frozen ...plain frozen...not the ones with sauces. Start using herbs and spices to give your foods flavor. Eat whole grain rather than processed....limit starches if you can...
Almost everything you consume has some natural sodium in it. For instance, one stalk of celery has approx 25 mg. A medium tomato has approx 35 mg.
Perhaps your doctor can recommend a nutritionist you can meet with who will help you with food values. The American Heart Association is also a good source of info.