This guide is for iPhone owners that would like to share their Internet connection with their laptop.the blackra1n+blacksn0w hack is a pain, as this combination will make you loose connection randomly and is buggy on the iPhone 3GS at least.
1.You need a jailbroken iPhone(i will not add details on how to do this in this guide)
2.the latest iTunes revision installed.
3.The sinfuliphonerepo.com source in your installer/store of choice.
first: i assume your device is already jailbroken, so head to your installer repository management option and install the sinful iphone repo(http://sinfulliphonerepo.com/). once is installed and refreshed, then navigate to the repository inventory and install the enable tethering package. at this point; you should reboot your device and you will have the tether option in you network setting.(if not then reset network settings)
second: initiate the tether connection by plug in in your USB cable or pair your iPhone with your laptop using bluetooth. you can do this by accessing your bluetooth interface and under devices, right click on your device and choose the connect using - access point
after you done that; you can now, add a shortcut to your desktop; by rigth click on the device, and create a shortcut. the shortcut will be placed in your desktop, this will make connecting to the device faster and easy, to connect: just right click on the device shortcut and click connect using - access point.
Update 1: shortcut part added because of a question by Rahul B. thanks for bringing that up to my attention.