Iphone tethering

I would like step by step instructions on how to tether my iphone (3Gs with 32GB) to be able to access the internet via my laptop. I don't want to do anything risky. I regularily go to the Apple itunes store and download applications and music. So in other words, I want all the advantages of tethering without any side effects. There are hundreds of articles online on how to do this but I want to work with a real techie that can do this with their eyes closed and have done this sucessfully multiple times. My carrier is ATT and I live in the United States. I will pay 50% upon completion of the work, 25% in 30 days, and the other 25% in 90 days to make sure that there are no negative side affects to the applied tethering. Thank you for reading my post. Copy paste responses will be ignored.