Is it possible to upgrade iPad 5.1.1.(I believe) iOS on a original, first addition iPad probably?

[iMore Question]

I used my phone 100% for all my needs...phone died a slow painful death in a large cup of coffee, that I didn't realize it was drowning...lol. No fix-did the rice thing ASAP and drove to see if fixable and nopers. Anyway back to my ? I have no cmptr so NO access to ANY Internet. No $ til 2/1 so was freaking out...lol. My AUNT gave me her iPad, the first one on market it, I think. It's a 5.1.1- I believe. I does work somewhat BUT most apps need 6 at the MINIUM, or if they do d/l once I click the icon, it looks like its opening then instead takes me to home screen, or if it does "open" it just waits until you press open or start or log in to just randomly close app and take me to home. PLEASE ANYBODY HELP ME! Any advice to upgrade or to idk have suggestions on this very LARGE HEAVY device I'd be so greatful because I'm 28 and a single mom to 12yro. Due to 6 back surgeries in 5 yrs. plus living in a town of maybe 600 ppl, I'm unable to jump in the car to drive 25 miles to go library, to use their computer. We have tiny library in town open m,w,f 4-6pm with 1 computer and it's after school hours so, the lil ruggrats are on it about 95% of the time including my own...haha. So any help with this very generously given iPad 1? Original? What ever it's called..haha!
(One more completely out there question, I read these devices need some sort of anti-virus-malware-spyware program because of issues with this device? I'm so confused!!!)

Thanks in advance,it's truly appreciated, more than you know. (And thanks so much for taking your valuable time to even read this abnormally long question and my life story)

(Yes, I am a huge yapper and babbler, I DO WANT TO APOLOGIZE for all my babbling, and probably sharing way TMI about me and not enough information about my issues)

 

[kch50428]

iOS 5.1.1 is the last version of iOS that the original iPad is capable of running.