Let me please start by saying that I am not techy so please keep it simple!
I have an iphone 3GS which was jailbroken on 4.1
I was then told by Orange that the phone has been unlocked and that I could update it. I think I updated it to 6.1
So I tried to so this and a 'sim card not inserted message came up'
I downloaded redsnow and a 4.1 restore.
I have it and read that I should change it to DFU so I did.
Then I selected an IPSW and then pressed jailed break
Now I have a blackscreen and a 'could not find mux funtion error'

Could anyone tell me (in simple terms) what to do please?
Thanks for the help