If you want to transfer all your data, settings and apps to your 4S, you restore to the backup. If you only want to transfer data synced to icloud.com, just sign into the same iCloud account in Settings>iCloud and turn on iCloud syncing for the data you want to transfer.
If you want to restore to an iCloud backup, first be sure that your 4S is running the same or higher version of iOS as your iPod. If not, update your 4S. You will then have to erase the phone and go back through the initial setup screens. 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. When you're done, go to Settings>General>Reset and tap Erase All Content and Settings. Then go through the setup screens on your phone and when given the option, choose Restore from iCloud Backup (see image below). Be sure it is connected to wifi and your charger as this will take some time to finish.