How to use your I cloud space, coz my phone still saying it full

iCloud storage is not the same as storage on your iPhone itself

You can’t buy more storage on your iPhone itself but here are two links that can help you to free up storage on your iPhone:

https://support.apple.com/en-us/HT201656

Optimizing photo storage on your iPhone can help a lot

https://support.apple.com/en-us/HT205703

If your iCloud is saying it's full, then - Manage your iCloud storage - Apple Support.

nelsa128 wrote:

I’m renting 200gb but still it says it full what can I do ?

Then the message is referring to you device's storage being full --

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