Photo Booth is a fun Mac application that is pre-installed on your Mac. It makes it easy to take pictures of yourself using your Mac's built-in iSight camera. Photo Booth includes a number of effects and backgrounds that you can use to make your Facebook, Twitter and iChat profile pictures more interesting and fun, too.
Snap a Photo
Launch Photo Booth. (It's in your Applications folder.) Click the Effects button to see a grid of effects. You can click the arrow buttons to see more effects. Select an effect you'd like to use by clicking on it. Now, look into the iSight camera, smile (or make a goofy face) and click the red camera button to take a picture. You'll see a thumbnail image of your picture at the bottom of the window.
Set Your iChat Buddy Icon
In Photo Booth, click the picture you'd like to use and then click the Buddy Picture icon. iChat will open and let you resize and position the picture. Click the Set button to save.
Set Your FaceBook Profile Picture
Drag the picture you want to use from Photo Booth to the Desktop. Go to the Facebook web site (using Safari or another web browser) and login. Click the "Profile" link (in the top-right part of the web page, next to Home). You'll see a large version of your current profile picture in the top-left of the web page. Click your profile picture and follow the instructions to select your new picture (the one you had dragged to the Desktop).
Set Your Twitter Profile Image
In Photo Booth, drag the picture you want to use to the Desktop. Next, sign-in to the Twitter web site. Click the "Settings" link and then "Profile". Next, click "Change Image" and follow the instructions to select your new profile image.