In the Messaging app, tap the compose icon, and then tap the plus (+) icon to enter a contact.
Repeat for each contact to whom you want to send the text. If you’re entering a phone number (not a contact), simply type it in and press Return in each instance.
NOTE: Replies from any of the recipients will come back to you only, not to the group to which you sent the text.
Search a conversation by keyword:
Tap the search field at the top of the Messages list.
Enter your search term, such as a name or keyword like ‘drinks’. As you type, potential matches will appear.
Browse the results to find the message you’re looking for.
What is iMessage?
iMessage is an Apple messaging service for anyone using an iPad, iPhone, iPod touch, or a Mac running Mountain Lion or later. With iMessage, texts are free for iOS or Mac users over Wi-Fi. If, however, you want to send a message (or you receive one) from a non-iOS device, you can still do so. But in these cases, your text will be taken from your monthly (wireless) texting bucket. Using iMessage, you can send texts, photos, videos, locations and contacts. It even has a cool chat-like feature that shows you when the other person typing, indicated with a grey ellipses icon.
To set up iMessage:
Go to Settings and tap Messages.
Turn on iMessage and then tap “Use your Apple ID for iMessage.”
Enter your Apple ID username and password. Then tap Next.
Tap Send & Receive, and then choose which email addresses and phone numbers you want people to use to send you messages. Do the same for the remaining options.