All iPad users by default get 5 GB of free iCloud space. And if you need more iCloud space then you can purchase from Apple. List below are simple instructions to get more iCloud space.
Step 1: Tap Settings on iPad home screen and navigate to iCloud option.
Step 2: Then tap Storage & Backup under iCloud settings. This should display the Total and Available iCloud Storage.
Step 3:Now to purchase more storage space, tap Buy More Storage option.
Step 4: Under Choose an upgrade section, select the required storage plan then tap Buy. The different plans include 10 GB, 20 GB and 50 GB.
Step 5: Sign in to iTunes Store with your Apple ID to complete the purchasing of iCloud Storage space.