Understanding Your Inbox.The Facebook inbox is the place where you can read all of your private communication on Facebook, including your chats. In addition to reading and sending messages, you can also use your Facebook inbox to: Send and receive email.
You can sign up for a Facebook email address that you can use to keep in touch with people who aren't on Facebook. You'll be able to view all of the emails sent to that account right in your inbox. To sign up for Facebook email, click Claim your Facebook email at the top of your inbox.
Receive text messages.
If you link your cell phone number to your Facebook account, all of your text messages will be forwarded to your inbox. Text messages from your Friends will be grouped into conversations along with the chats and messages you've exchanged.
While you can communicate publicly with wall posts, Facebook messages give you a chance tocommunicate in private.
To Send a Message:
On the top toolbar, locate and click on the Messages icon . A drop-down menu will appear. Select Send a New Message Click the To: box and type the name of the person you wish to message. Click the Message: box and type your message.
When you're satisfied with the message, click Send. The message will be sent. You can also message someone directly from their profile. Simply click the Message button in the top right corner of their profile.
You can also: Type multiple names in the To: box to address a message to more than one person.
Type a link into the message. Facebook will automatically insert a description and thumbnail image for the link. Click the Attach button to send a file from your computer.
Click the Picture and Video button to take a picture or video with your webcam and include it in your message.
Check the Text Message checkbox to also send your message to the recipient's phone.
"Facebook Tips: Facebook Messages Send and receive email"