I would really appreciate if someone help me to unlock version 4.3 on my iphone 3gs

 haha...ship garera pathau, ma gardinchhu! 

 hasayou yar....but i am loooking for serious suggestions....anyone????

jailbreak it first:
first, update itunes to 10.2.2 if its an older version, use updated itunes to update your phone to 4.3.3 firmware if it's an older firmware.
then go to http://www.justmobilephone.com/download-redsnow/ and download appropriate version of redsnow for your pc/mac. then go to http://www.iphoneheat.com/2011/03/download-ios-4-3-1-firmware-for-iphone-ipad-ipod-touch-ipsw/ and download the firmware on which your iphone is currently running. if it's not listed there, find it through google search and download it. move it to desktop. start redsnow you downloaded earlier and follow the steps. firstly, it'll ask to choose IPSW, which is the firmware you downloaded. select it and let it work. then you'll have to put your phone in DFU mode, instructions will be shown on the redsnow window but it'll take a few times to get it right. after that, your job is done, everything will happen on its own.
to unlock: install a software like ziphone (there a more, you can find them through google) and let the magic happen

 hello , download same farmware which is in your phone's (4.3) and download the latest redsn0w and use fellow this links 
u can successed to jail break and unlocked 

 https://www.youtube.com/watch?v=yz5L5UNObxw

 I heard that there are a lot issues with a jailbroken iphone. Is it true?

I want install "backgrounder" app but I'm not sure if it's worth jailbreaking the phone.

thanks all
 i try to follow the instructions mentioned in above video... but i cant see the firmware in my itunes

You can unlock I-phone 4 or 3GS easily using the remote unlock service at here Simpleunlocking.com 
i have unlocked at here.