How to know if I have apple care+?

Check Your Service and Support Coverage - https://selfsolve.apple.com/agreementWarrantyDynamic.do - "Review your Apple warranty status and eligibility for support and extended coverage." Requires a hardware serial number.

Applecare for different products - http://www.apple.com/support/products/

AppleCare+ or any extended AppleCare warranty is a separate purchase and will be billed separately or itemized on your receipt if purchased at the same time as your device.