Open the Messaging screen, touch New message.
Add the recipient(s).
If more than one recipient is entered, you will be asked to choose between a group conversation and a individual message.
Touch Group Conversation to allow all of the recipients to be viewed by each other so they can respond to you and the group. The message is sent as a multimedia message (MMS).
Touch Individual Message, so that none of the recipients can see the other recipients (similiar to BCC). Each individual can only respond to you.