My iphone storage is full. How can i transfer my stuff to my icloud storage?

Try uploading to iCloud Drive then you can delete it from the iPhone using Files App

If you had enabled iCloud Photos and then if you delete Photos and Videos from the iPhone then it is deleted from iCloud Photos too, and vice-versa. Also, it is deleted from all the devices that use the same Apple ID.

And if you happen to take a backup either over iTunes or iCloud after deleting Photos and Videos all the photos are deleted from the backup (iCloud/iTunes) too when you take the backup next time.