Q: How do I upgrade to 8 with my original Ipad that only will go to 5.1.1

You can't. 5.1.1 is the latest you can get.

Matt

A first generation iPad can't be updated past 5.1.1.

(122456)

You don't.  The First generation iPad cannot be updated to iOS 8. it stops at iOS 5.1.1.

What part of no don't you understand?

No. If desired, click here and try following the instructions.

(122457)

It cannot be done.

As Neil points out, you may however be able to get compatible versions of Apps for iOs 5.1.1.

You'll need to get/download the App on iTunes on your computer, and then follow the instructions in the link provided by Neil.

Install the latest compatible version of an app on an earlier version of iOS or OS X - Apple Support