NOTE:  You will need an Apple ID in order to back up your data to iCloud.  If you do not have one, you can learn how to create one here:  Create an Apple ID

1. Open the Settings app:

2.  Click on your Apple ID (at the top, you should see your name):


2.  Click on the iPhone/iPad in the list of devices (it should say This iPhone/This iPad).  Enter your Apple ID password if prompted:

3.  Click on iCloud Backup:

4.  If iCloud Backup is not enabled, turn it on.  Click Back Up Now:

5.  If you have never backed up your phone, this process may take up to 30 minutes, depending how large your backup is.