You need Mac OS X 10.3 or higher to run Skype.
1.Quit Skype
If you have an earlier version of Skype running, you need to quit it.
2.Open the Download window
Open your web browser’s Downloads window and double-click on the blue Skype icon.
If a warning dialog opens, click Continue.
3.Drag the Skype icon to your Applications folder
If you have an older version of Skype installed, you’ll be asked whether you’d like to replace it with the new one. Click Replace.
4.Open Skype from your Applications folder
After you’ve ejected the Skype disk image, you can run Skype.