Welcome to glider parenthood.
There are a number of good glider feeding plans that you can choose from. These each have a staple recipe for a nectar like mixture that will provide your gliders with the protein, vitamins and most importantly the calcium they need. I have links to these widely used feeding plans on my web page to help you locate the information and decide which one you would like to offer your glider.
http://www.gliderkids.com/contact.html
Look over all the feeding plans and their instructions. Ask questions here to help you decide which will work best for you. Once you decide then you can purchase or order online the specific supplements and foods needed to prepare the one you choose.
For now, you can feed your glider some plain cooked egg or boiled chicken for protein. Offer about 1 TBS protein along with 1 TBS fruits and 1 TBS vegetables per glider each night.
Your glider may have eaten all that was necessary but if you fed more than a total of 3 TBS of food per glider, there would be lots left over. Gliders have very small stomachs about the size of the tip of your thumb. They eat small amounts off and on all night long. If your glider is young, it will not eat the full adult feeding of 3 TBS of food.
Your gliders will NOT starve them selves. They will eat what is available. If you do not offer the pellets or corn - they will eat the other foods you serve. You can leave a few pellets in the cage during the day for 'snacking' but take it out at night to encourage them to eat better foods.
Corn is very high in phosphorus and that can through their calcium absorption off if fed every night. My gliders only get corn as part of mixed vegetables once a week. Other nights they get a different fruit and vegetable so that they get a wide variety of fruits and vegetables each week.