You can record with any of the Camio apps for Android, iOS, Chrome/Firefox by pressing the Record button.
If you have the app installed, tap the recorder icon in the tab bar, then press record!
You can also switch between your device's front and back cameras if your device has two cameras. To return to your feed, tap the "Back" button in the upper left.
If you're recording with your computer using the Chrome browser, you can still lock your screen while continuing to record.