My storage space is full. However, my iCloud space is plenty. How do i increase my storage availability ?

If you're referring to your device's storage, you cannot change (add to it) that as it's permanent. Follow to the steps below --

https://www.youtube.com/watch?v=bnhuHSv_WrI

My storage on my I-pad is nearly full I have deleted some pictures and apps and have added to my iCloud storage. How do I decrease the grey on my I pad storage?

My storage space is almost full, however my iCloud space has been updated

How do I decrease the other on my I-pad storage?