The storage you get for iCloud is used for backups, which can't be accessed, photos, if you use iCloud Photo Library, files you decide to add to the online storage...
iCloud can be accessed at www.icloud.com, through a browser on a computer.
The 1 TB you purchased for iCloud don't extend the storage space of your iPhone. From your screenshot, it looks like you own an iPhone with 16 GB storage.
From your screenshot:
In Storage - Manage Storage, you can decide which apps you need, or which ones to remove.
In iCloud - Manage Storage, you can see how much storage space your photo library needs, which iDevices backup to iCloud, the storage space your email account needs, documents and data saved to iCloud.