Iphone 4s wont update to IOS 7?

So I just got an Iphone 4s form ebay which works perfectly. But Im stuck on IOS 5.1.1 when I got the phone everything was reset so I had to set it up. When I try updating to ios 7.0.4 it says something about an Error. I have been trying ever since i got my phone 5 days ago. And it hasn't worked what do i do?

Added (1). For those people sayingthat Iphone 4s is too old for ios 7, you're wrong. If it wastoo old to run Ios 7 then i wouldnt even see the update… And. As far as im concerned iphone 4 and up technologies receive ios7 so please just answer if you actually know about this not some random crap.

Don't you know apple only support their devices for three years, after that your on your own stuck with the old operating system

to old to run iOS 7

If its the same error i get, youll need to download a thing called microsoft fixit to change your computers host file or something like that. Run the program then restart your computer and you should be able to update your iPhone.