How to update my iPhone 3gs to ios 5.1.1?

I currently have my iPhone 3gs at ios 4.1 and I want to update to ios 5.1.1 because from what I've heard ios 6 is a battery killer and just an overall bad update. I tried just downloading the.ipsw file from the internet and then ---clicking update. But that didn't work I got error 3194, i tried deleting the #gs.apple.com line from my host file but that still didn't fix the problem.

You can't download any iOS besides the latest version from Apple. There are illegal downloads available, but I don't recommend them.

Did you save SHSH blobs for IOS 5.1.1?

You can please go to nearest store and update it.