I need help of iCloud

The 5GB is free. You can by additional storage (replaces the free 5GB, not adds to it); pricing is charged monthly(there is no annual option). 50GB $0.99 p.m., 200GB $2.99 p.m., 2TB $9.99 p.m. (UK £0.79, £2.49, £6.99).

Buy more iCloud storage - Apple Support

Yes, it's a monthly subscription service. If you stop paying the storage will revert to 5GB.

Reply me

These forums are not Apple Support; the people who answer are volunteers who do so unpaid on their own time, so you won't always get a quick answer. It just depends on when someone who feels he can help sees you post.