Q: icloud to iphone

First, clear the iPhone for re-use :

What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support

Update to the latest iOS 9.2.1 by connecting to your computer iTunes.

Note: All content are forever tied to the Apple ID used to obtain them.

Content cannot be merged or transferred to another Apple ID.

Use family share to share your purchases with your son.

Family Sharing and Apple ID for your child - Apple Support

Share purchased content with Family Sharing - Apple Support

hello i want to suggest you to connect your iPhone with your iTunes on your notebook and just go on with hard reseting it by pressing its homes and lock wake up button at same time when it is off don't leave the buttons keep pressing them till you see iTunes on your iPhones screen and it will ask you to connect it again to iTunes on your notebook this is know as recovery set up mode so go on and your iPhone will again start up with the set up

Sounds like you've got an iPhone 4 and not a iPhone 4s.

iPhone 4 cannot update beyond iOS 7.1.2.