As suggested before:
Pellets:
Add a quarter of pellets to their bowl. Each week add a bit more pellets. This will teach your amazon that this food. Chances are they don't know. You want to do this slowly or your amazon may starve to death. It'd probably take about a month. Try different sizes and kinds (I used zupreem fruit blend) to see which they like best. If your concerned about the amount of waste of pellets you'll have the most you can do is go down a size (ex. Budgie use finch size).
Veggies and fruits:
Eat some in front of your amazon. Don't over do it. Just try one at a time and make lots of excited and yummy noises. If they come over offer them some. If not still offer them. Leave it in a bowl as sometimes they might get curious and nibble at it. I find it best to cute the fruit in bite sizes for budgies, but into little sticks with amazons. Also, in the beginning see which fruit and veggie their more open to try trying.
If they don't like something then don't insist on it. One of my amazons loves almost anything but the other is a picky eater. He only likes crunchy fruits and veggies. I often try my best to please his tastes.
Seeds:
Once your amazon has converted to pellets try to get him to try different seeds and dehydrated fruits and veggies mix. I make my own depending on each parrot's taste. You can also find others. I suggest you offer some mixes that have dehydrated fruit and veggies in them.
