You're welcome. Restoring to an iCloud backup has to be done in the initial iPhone setup process. If you have any data on your phone now that is not in the backup that you want to save (other than the contacts and calendar, which are on iCloud) you'll need to do that first. When you're ready,go to Settings>General>Reset and tap Erase All Content and Settings, which will erase the phone. You will then go through the setup screens as you did when the phone was new. When given the option, choose Restore from iCloud Backup (see image below). Be sure you are connected to wifi and your charger as this will take some time to finish. Just so you know what to expect, this is from an Apple support document:
After your device restarts, your settings and accounts are restored and Backup starts downloading your purchased music, TV shows, apps, books, Camera Roll, and other content*. You may be prompted to enter the passwords for all accounts enabled on your device.
A progress bar will appear underneath the apps that are being downloaded. To prioritize the restore of a specific app, tap its icon. Restore will attempt to download the same version of the app that you had installed previously. If that version is no longer available, the latest version of the app will be restored.