If you followed the links, you don't have to install anything, it installed itself. To check, go into Settings/General and scroll down to see if you see "profile." If so, select it and you should see a profile for AT&T that says "Unsigned" and then has the following Description: AT&T US - BenM.at
Go back to General, scroll up to Network, select, then go down to Internet Tethering, select and make sure it is turned on. Then just hook your iPhone up to your laptop via the same USB cable that you use to sync it to your computer and you should be good to go.