Camera roll photos are included in your iCloud backup; restoring the entire backup should recover them. To restore to the iCloud backup of your old phone you have to first be sure your new phone is running the same iOS version or higher as the one you backed up. If it isn't, you'll have to update it first.
Restoring to an iCloud backup has to be done in the initial setup process. If you have any newer data on your phone now that is not in the backup that you want to save you'll need to do that first. Then go to Settings>General>Reset and tap Erase All Content and Settings. 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.