Does it accurately list the full amount of Charge Orbs you have at the moment? Sometimes, the Charge Orb Disappearing glitch will happen and affect them visually. If you need to check how many you really have, use the "Loot" tab in your Inventory screen, in-game, or the "zOMG" tab in your site Inventory.
Inside the Null, open your Inventory and select a ring you wish to level. Once it's highlighted, 3 buttons should appear. "Upgrade", "Salvage", and "Swap".
Upgrade: Allows you to raise the Charge Level (CL) of any ring you choose. Depending on the level, the number of Charge orbs necessary per 0.1 charge level increases.
Example: To reach CL 2, it takes 1 Charge orb per 0.1 charge level. Level 3 takes 2 charge orbs per 0.1 charge level, and so on and so forth, increasing up to Level 10. Beyond CL 10 is a different matter.
Salvage: Allows you to destroy any ring of your choice, and harvest the Charge Orbs from it. Beware! When salvaging a ring, you only receive HALF of the Charge Orbs inside of it that makes it that level. Only salvage rings that you are completely sure you can locate again, and/or have doubles of.
Example: I salvage a CL 2 Mantis. Since it took 10 Charge Orbs to make it CL 2, I would only receive about 5 Charge Orbs in return. Thankfully, this was only an extra version of Mantis, so nothing of value was lost.
Swap: Allows you to swap the CL of any two rings. But you can only do this once every 24 hours.
Example: I would take my CL 10 Solar Rays, and my CL 12 Adrenaline, and place them in the Swap tray, and swap their levels. But I made a grave mistake, but have to wait until 24 hours from now to fix my issue.