To get a specific user's attention, you can “ping” them by writing {{ping|Username}} on a Talk page, which will send them a notification. Some Wikipedians have hundreds, or even thousands, of pages on their Watchlists so this is a good way to get their attention.

If you're addressing a user on their Talk page, they will be notified whether or not you ping them. If you're addressing a user on your own Talk page or an article Talk page, you'll need to ping them.

Remember to sign your message!

If you want some practice, try introducing yourself to a classmate on that classmate's Talk page. To find another Talk page, go to the Students tab and click on the username of the student you'd like to leave a message. Then click Talk in the upper-left corner of their userpage.