To send a message to someone who is not on your Friend List, click the Send toolbar button. Or, if you're using the Windows version, you can also click the Pager menu and choose "Send a message..."

You can only send instant messages to someone who has a Yahoo! ID and is currently connected to Yahoo! Messenger or is online in Yahoo! Chat or Yahoo! Games.

To control which alias (profile) you use to send an instant message, locate your ID displayed in the upper-right corner of the message window. Click the down arrow to the right of your ID, and then choose any of your aliases from the list. If you don't yet have any aliases, visit the profiles page and click the Edit My Profile link.

Tip: You can send an instant message to more than one person. Just click the Send toolbar button and type in their Yahoo! Ids or profile names, separated by commas (e.g., kyle, stan). With the Windows verison of Messenger, you can also send a message to an entire group. Right -click on a group name and click "Send IM to online members..."