iTunes won't update to 11.0.1
So I need to update my iphone to the new iOS 6.1 but when I try to update to iTunes 11.0.1 it comes up saying this: 'Errors Occured while installing the updates. If the problem persists, Choose Tools>Download Only and try installing manually'. It wont install manually and I tried using iTunes64setup.exe and that didn't work either.. I don't know what to do now and I'm not great with computers..please help!