I have an iPod Touch but I don’t have a wireless router. How could I use any of the features that require wifi. After searching for a way to connect my iPod to the internet, I was able to use the Internet Sharing feature on my iMac.
Before you start you need to turn AirPort: On
Step#1:Open System Preferences / Sharing
Step#2:Under Service click on Internet Sharing, for Share your connection from: select “Ethernet”, for To computers using: select “AirPort”
Step#3:Click AirPort Options, choose a Network Name, Enable encryption, choose your Password, click “OK”
Step#4:Under Service check the Internet Sharing box, and click Start
When you turn on your iPod Touch and open Safari, a list of networks will appear, choose the one you made and enter your password. Now you can enjoy all the wireless features on your iPod Touch.
I don’t have an iPhone but I suspect this will work just the same.
Paul Minshall 
Thanks for this! I tried the instructions on Apple’s own site, but these are what finally worked! Thanks for making them easy to understand and for sharing them with all of us!
Wow, best description i have come acros thanks so much
thanks for that!
The most simple and effective explanation I found after an hour searching. THX
you saved my day! i had Airport configured, but could not get on the Web with my new toy ’till i Googled my question ‘how iphone connects to imac’ and got replies with some info, but not this straight foward connection data (there may be, but yours was 1st)…Thanks, again