Stole ipad how to secure data and get it replaced?

While Apple's AppleCare+ plans for iPhone have optional (additional cost) cover for theft, available AppleCare+ plans for iPad do not cover loss or theft of iPad devices.

As for your stolen iPad, start here:

Locate a device in Find My on iPad - Apple Support

Here is Apple’s advice for lost or stolen devices:

If your iPhone, iPad or iPod touch is lost or stolen – Apple Support

Use the Find My app to locate a lost or stolen device – Apple Support

If the Find My iPad feature was enabled prior to it being “misplaced”, then if active, you would stand a good chance of locating it. 

However, if the feature was not activated prior to being misplaced - or the iPad has been inactive for more than 24 hours, the last known location will not be available - and the opportunity to use technical means to recover the iPad have been lost.

Sorry about the theft. I know how troublesome that can be. If you have AppleCare+, contact Apple Support and report the loss. They will tell you how to proceed. If you did not purchase AppleCare+ for your iPad, then Apple will not replace it, at least not for free. You'll need to purchase another iPad.

As to what to do to secure things, see:

If your iPhone or iPad is lost or stolen - Apple Support

Regards.

Apologies about the misinformation re. theft protection for an iPad. I was garbling information applicable to the iPhone. On an iPad, AppleCare+ only covers accidental damage, not loss or theft. Thanks to LotusPilot for the correct info.