How do I get Safari version 11 on my ipad

Safari is an integral element of iOS - that is updated along with the installed version of the System Software. Safari cannot be updated in isolation.

Your iPad2, being a very old model of iPad, cannot be updated beyond iOS 9.3.5 (WiFi Only) or iOS 9.3.6 (WiFi+Cellular). As such, you’ll not be able to update your installed version of iOS - or the related version of Safari.

On an iOS device such as an iPad, Safari is part of the operating system. If you have, as your post indicates, an iPad 2, you can't update that beyond iOS 9.3.6. So, no iOS 11. You'll need a newer iPad.