I am not going to be so hostile towards you as some of us forget that others are not so technically advanced!
If you are sharing your Apple ID everything everyone does on their devices are shared throughout all of them and uses the same icloud storage.
This does not mean that you can't fix your own and enjoy your iphone.
Create one now at id.apple.com. https://appleid.apple.com/account#!&page=create
Then, on your iPhone, go to Settings >[yourname], and sign out
Make sure to choose to 'keep on this iPhone' when prompted what you want - toggle on
Then sign in with your new Apple Id account, and then choose to 'merge' the Contacts from your iPhone to your iCloud account.
Also, sign out of the old Apple ID: Settings > Messages,
Settings > Facetime and
Settings > iTunes & App Stores.
Then, sign in with your new Apple ID.
Hope this works.