Summarize:

Look for a gray wheel on your iPad screen labeled Settings. Tap it, and you'll be greeted by a screen that lets you change every conceivable facet of your iPad's operation as well as the apps you have installed. Not every app pushes its data to iCloud by default. Apple only gives you so much storage space on the cloud, so you have to give apps permission to stake out space there. When prompted, give your permission to merge your reminders on iCloud. All of your reminders created on all of your Apple hardware can now be viewed and edited on any Apple device. After you've pushed your reminders to iCloud, you can share them with other people who may need access to them, such as your spouse or work colleagues. Open the Reminders app, select a list, and tap Edit. The Sharing option should appear. Tap it, then tap Add person to share the list.
Open the Settings menu. Tap the iCloud icon to view apps that can sync with iCloud. Scroll down to the Reminders app and tap its slider.