How do I upload photos onto my iCloud and delete them on the phone ?

I pay for 50g storage and have about 23g data to store , how do I upload photos onto my iCloud and delete them on the phone ? Currently if I delete on the phone it also deletes on the iCloud . I’ve tried backing up my phone but it never completes back up. I’ve tried syncing and backing up via iTunes but I still don’t have anymore storage . The iPhone is automatically deleting my important applications to make space .IM SOO FRUSTRATED!!! PLEASE HELP

[Re-Titled by Moderator]