How to get flash player on my ipad 3 ?

You don't. APple and Adobe don't play well together. Adobe never made a version of flash that met apple's requirements, Apple was never happy with what Adobe made so Flash is not natively supported. YOu can look for browsers that support flash, such as Puffin, Skyfire, iSwiffer and others.

There likely won't be much growth in this area since Adobe has ceased all production on mobile flash so it is in essence, dying technology....however as with anything, it'll be a long drawn out death that'll likely take years for it to totally go away.