The suggestions below can be applied to any citrus fruit, including Oranges, Sour Oranges (Bitter Oranges, or Trifolate Oranges), Blood Oranges, Limes, Lemons, Grapefruit, Pommelos (though you only want the outer rind in the peel recipes with these), etc.

Oranges do not dry well, they tend to go all to sawdust! But there are other ways to preserve them that result in enjoyable treats.

The oranges can be juiced, and the juice may be canned.

Oranges can be canned. Cut off the peel, just inside the backs of the slices, then work the slices out of the membrane. Can in syrup, or juice a few and can in natural juice. Pineapple juice also works well in place of syrup.

Oranges may be candied. You can do the orange slices without peels, or you can just slice the whole orange with peels, and candy them, the same as you would orange peel (though you skip the rinsing).

You can scrape off the zest, dry it, and use it for baking, in which case you throw away the bitter parts. It can be ground and dried for long term storage.

You can candy the entire peel, in which case the bitter parts get candied also and you prepare it in a way that gets rid of the bitterness. Candied orange peels can be used in place of orange zest in recipes, they can be dipped in chocolate for an elegant gift or treat, and they can be enjoyed plain. You can replace the water in the candy recipe with orange juice for a stronger flavor, or with pineapple juice for a tropical burst.

The syrup from the candied peels can be used to add to jam, or to use for sweetening tea or other beverages.

You can dry peels, chop them up, and use them in potpourri.

You can cut off the zest in large chunks, dry it, and use that for spiced cider blend.

And of course, you can make marmalade with the whole orange.

Oranges are one of the more flexible fruits, and the whole orange can be used for some things.