what to do if my i phone 6 with 16GB IOS 8.2 display gets cracked?

Sorry, but dropping the phone is not covered by the warranty, you will have to pay for the screen to be replaced.

Screen repair service pricing
Repair and replacement costs depend on your iPhone model and your AppleCare product coverage. Apple will run a diagnostic test to determine whether your iPhone has experienced additional damage. If it has, or if it needs other repairs, you may need to pay an out-of-warranty service fee. Accidental damage isn't covered under the Apple One Year Limited Warranty.

Model	Screen repair cost
iPhone 6	$109
iPhone 6 Plus, iPhone 5s, iPhone 5c, iPhone 5	$129

Plus a $6.95 shipping fee, if required. Fees are in USD and exclude local tax. Pricing is for service through Apple. The final service fee we charge will be determined during testing. Pricing and terms vary for service through an Apple Authorized Service Provider.

copied from Service Answer Center - iPhone

If you purchased AppleCare+ for the gadget, I believe you are entitled to repairs for TWO accidental damage events for a service charge of $79 apiece. It costs $99 and must be purchased within the first 60 days of having acquired the device. You do the math.