iPad 1 update from 5.1.1 to 7.1

How can I update iPad 1 from iOS 5.1.1 to iOS 7.1?

I tried checking for updates but I get a message "your software is up to date".

Solution 1:

You can't install iOS 7 (or even iOS 6) on an iPad 1.

^{Source: http://www.apple.com/ios/features/}

The last version of iOS capable of being installed on an iPad 1 is iOS 5.1.1 and since this is the version that you are currently on there are no updates available.

Solution 2:

This just isn’t possible.

From Apple's Support:

iOS 6 is not available for the iPhone 3G or earlier, iPod touch (3rd generation) or earlier, and iPad (1st generation).

iOS 7

System requirements
iPhone 4 and later
iPad 2 and later
iPad mini
iPod touch (5th generation)

iOS 8

System requirements iPhone 4s or later iPad 2 or later iPad mini or later iPod touch (5th gen)