Greetings LouisDa13,
Welcome to the Apple Support Communities!
I understand that you received an iPhone 4s from a friend, that is not locked with a Find My iPhone account, which you are having issues setting up. The first troubleshooting steps I would recommend in this situation are located in the attached article.
Get help activating your iPhone - Apple Support
If you still have issues setting up your iPhone, please let me know specifically what screens you are seeing and what, if any, error messages or alerts you receive as well.
Cheers,
Joe