How to Send a Message to All Friends on Facebook

Steps:
STEP 1: Log into your account

STEP 2: Go to your home page

STEP 3: Click Messages link
Click the Messages link or the Messages icon in the Facebook toolbar.


STEP 4: Click New Message
Click on the New Message button on the Messages page. Messages can only be sent to 20 friends or e-mail addresses at one time, so you may have to send more than one message to include everyone. Type in friends' names from your friends' list or enter their e-mail addresses into the "To" field of the pop-up window.
You can also set up a group with all of your friends in it to send a blanket message to all group members. Be aware that the 20-person limit still applies when you're messaging a group.

STEP 5: Write your message and Send