NEED MORE GB ON MY IPHONE 5s?

No way to add memory to an iPhone. You must have lots of photos, videos, music, or apps. Delete the ones you don't need anymore. You can always get apps back if you need them later. You can back up your photos and videos to iCloud and delete them off your phone.

You'd have to get a 32GB model. Can't add to what you have.

Storage space can't be upgraded in iPhones. You'll need to replace the phone if you want more storage.