Welcome, Melissa. You're right, it's not good for her to eat oranges every day. Get a bag of frozen blackberries or mixed berries; they're much healthier. Peas and corn are also not good except occasionally. The reason for this is that gliders need twice as much calcium as phosphorus in their diets; corn and peas are at the bottom end of the scale for that ratio. Much better vegetables are bok choy, cucumber and celery. Read this, it explains everything:
http://files.meetup.com/768852/Ratios.pdf
. There's also a list of fruits and vegetables in order of what's best to what's worst. There are recipes in the Resources: Nutrition tab above that have the ratios already figured out for you, so there's no guesswork.
Corn flakes are also bad for two reasons: they're made from corn, and they're dry. Gliders don't produce a lot of saliva, and they need juicy food. They also get a great deal of their water from what they eat.
You can get some plain or fruit-flavored yogurt -- no artificial sweeteners, though. That's good for protein and calcium as well. Use it as a "licky treat": put a little on your finger and offer it to her. She'll lick it off; be sure to get more before she's cleaned your finger, or she'll bite to try to get more. That's an instinct from biting a branch to get sap. This is a great bonding tool, as she'll associate your hands with good things to eat.
My main advice to you is to read! Read threads on diet, bonding, and behavior. Read old ones as well as the most recent; there's a lot of discussion going on all the time, and a wealth of information in some of the older threads. If you go back as far as a month, you'll find the answers to most of your questions, and to questions you haven't even thought of yet!