how do i report my ipad stolen

There is no mechanism by which you report a lost or stolen device to Apple.

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

See this:

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

You can use Find My to activate lost mode.

To report it as stolen, Contact local law enforcement.

Good Luck!