How to Add Phone Numbers to Groups on an iPhone
Sorting phone numbers into groups on an iPhone simplifies the use of those numbers. Grouping contacts enables you to send a text message to everyone in a group at the same time without having to select individual names. Creating groups is a simple task.
Add Numbers to a Pre-existing Group
Click on the "Contacts" widget to open your address book of phone numbers.
Select the "Groups" button from the top left-hand corner of the iPhone.
Select the group to which you want to add your contact. You will see your complete address book but with the group title on the top.
Select the contact you wish to add to the group.
Create a New Group
Connect your iPhone to your computer using the USB cord that came with it.
Open up the program "Address book" on your computer.
Go to "File" and select "New Group..."
Create a name for the group. You can add new contacts to your group through the computer, as well. It will automatically sync with your phone since your phone is connected to the computer. IPhones cannot currently create new groups (as of December 2010); it needs to be done through the computer.