this post will show you how to setup a wireless internet connection from your mac to your phone so that you can get internet through your phones 3g connection!
assuming you are allowed the personal hotspot functionality by your provider:
on your iphone goto settings > personal hotspot
if you dont have personal hotspot in settings, then you dont have the feature enabled by your provider. call them and see if they can activate it for you.
once in personal hotspot simply turn it on.
when it is enabled, it will provide you a password, and will allow you to set your own.
once the hotspot is up, it will appear as any other wireless network, with the name of your phone.
just connect as normal, and enter your password chosen in the settings of personal hotspot.
browse the net like normal!!!