If your iPad doesn't have any rear facing camera lens or a front facing camera lens (dot) opposite the home button, you have an original iPad 1 and the orginal iPad cannot be upgraded past iOS 5.1.1.
The hardware in the iPad 1 is NOT capable of supporting newer IOS versions.
Sorry.
The original iPad is nearing the 6 year mark (April 2016), it has not received any updates since 2012.
You may want to consider upgrading to a new or "newer" ( used ) iPad model.
To insure some future proofing, I would recommend looking for 1st Gen. iPad Air models or greater.
iPad 2 and 3 models are having some issues with the most current iOS versions now available.
And many current iOS features are not supported on iPad 2, 3 and 4 models, either.