how to change ISO on a jail broke 3gs

[nlicursi]

my 3gs is in 4.1 ISO and there are aps i cant use because of that. i would like to know how to put it to ISO 5. I'm new at this and I'm lost lol

 

[Jmills87]

If you have an official carrier just hit "update" in iTunes and then rejailbreak with the latest redsn0w. If you require unlock, create a custom 5.0.1 firmware with redsn0w or sn0wbreeze and restore that to preserve your baseband.

 

[nlicursi]

the phone was unlocked that i could use it on any carrier. i never jailborke it myself thats why im lost with all this.and i dont want to mes up my phone