Please urgent help, my iphone firmware V1.0

Dear all,
Please help me in this matter.
My friend got me the iphone from china and i was surprised to find it unlocked already, when i put my sim and turned it on i got a screem simlocked and i should choose OK or UNLOCK, i choose unlock and everything is working great.
I have a problem that i can't recieve any sms but i can send normally.

My major problem is this:
I checked my firmware and i found it V 1.0.0, i need to upgrade to version 1.0.2 so please can anyone help me and tell me what to do? how should i upgrade and use anysim?? I would like to tell you that i don't have the AT&T sim card. so please help me.
What are the steps i should do to have 1.0.2 with my unlocked V 1.0.0???

no would like to help?

hey man, all you have to do is follow the tutorials , wich can be found all over now...the best bet for you now would be this one http://hackint0sh.org/forum/showthread.php?t=6637
just follow the steps and it will tell you how to update your firmware, be aware that you will have to unlock your phone again...