From reading your previous posts - you're on an iPad2, correct?
Unless you have both an iOS 4 blob AND the blob from iOS 5.1.1 (and you didn't use over-the-air upgrade), I'm afraid you're stuck with the version of iOS you are running. If you have those blobs, you can upgrade to iOS 6.1.3 and then downgrade to iOS 5.1., which is jail breakable.
Otherwise, without those blobs, the only upgrading you can do is to iOS 6.1.3 - but without the ability to downgrade (and that iOS is not jail breakable).
So, whatcha got?
Marilyn