Celebrating birthdays on Facebook is a great way to show your friends you care about them. Facebook birthday celebrations are fun, inexpensive, and easy to do. Here's how:

What to Do What It Is How to Do It
Write on a friend's Timeline. Formerly called the "Wall," this public forum usually fills up with well-wishes on a person's birthday. Go to a friend's Timeline, find the Publisher below their cover photo in the middle of the screen, and enter your message.
Send a friend a message with a sticker. A sticker is the Facebook equivalent of a real world sticky piece of flair. There are stickers for all sorts of images, including birthday-related ones. Open a message window and enter your friend's name. At the bottom of the window, click the smiley face icon to open the Browse Stickers window. Select the sticker you want and it will be sent to your friend in a message.
Tag a friend in a status update. Status updates are your own posts to your friends on Facebook. You can add tags to posts to give a shout-out to the people you mention. Go to your Timeline and start typing a status into the Publisher. Enter the @ symbol, and begin typing your friend's name. You can then Select your friend's name from the list that appears, and when you post, they'll be notified.
Make a Thanks video. A slideshow video that lets your friend know how much you appreciate them. Navigate to www.facebook.com/thanks. Select your friend's name and then choose from photos of the two of you to create your video.
Call a friend. This is a good old-fashioned verbal birthday wish. Go to their Timeline, click the Info tab, and look for their phone number located under Contact Info. Use your phone to call them — and maybe sing!