Jailbroken iphone restoring it to 5.1 tiny umbrella?

Hi if anyone could help me with this i would be very grateful. I had a jailbroken phone but i stupidly tried to update it to iOS6 using iTunes. I can now not activate it because it isn't the original sim carrier. I have downloaded tinyumbrella and i pretty much know what to do, change the setting to set hosts to cydia on exit but tinyumbrella won't let me check it because it's greyed out. How do i check it? A quick reply would be very much appreciated!

Unfortunately you can't downgrade your iphone to any ios unless you have saved your SHSH blogs before upgrading to ios 6 using tinyumbrella. However if you have iphone 4 or 3gs (not iphone 5 or 4s) you can jailbreak it if its ios 6.0 ( not more like 6.0.1 or 6.1) then from cydia you can install an app to unlock it. If its the case this site can be very helpfull: www.jailbrea.kr! Am glad to help you.