Time Machine, an application in Mac, lets you automatically back up your entire system in Mac OS X v10.5 and Mac OS X 10.6 or later. Time Machine keeps an up-to-date copy of everything on your Mac--system files, digital photos, music, movies, TV shows, documents, and so forth. You can easily go "back in time" to restore files if you ever need to with the nice and clean interface it offers you.
What you should prepare:
1. OSX Leopard or above.
2. external hard drive (it must have enough space for the data you are going to backup).
How to backup data with Time Machine?
1. Connect your external hard drive with the Mac and open the Time Machine. Then "Select Backup Disk".
2. Choose the external hard drive as the target place where your Mac data will be restored. Then click "Use for Backup". If you have more than one hard drives connected, they all will be displayed, and you only need to choose one of them for backup. Make sure the hard drive you choose must have enough space for your backup files.
3. The Time Machine turns to "ON" status, and the counter has started for your "Next Bakcup". You can check the time left. When it reaches zero, the Time Machine will start to backup your data from Mac to the external hard drive.
If you want to pause or stop the backup, you can set the Time Machine "OFF", or just shut down it before the backup begins.
If you want the backup work continue, let it go as normal. When the "Next Backup" turns to "Backing up", there will be a small windows popping up, which is telling you the backing up process. During the backup time, make sure that you are not going to use your Mac, because this will take a quite long time.
Some useful tips
1. When the Time Machine is backing up your Mac data, the icon of the hard drive used for backup turns green, and it just looks like the icon of the Time Machine, which is very sweet. When the work completed, it will get back.
2. On the bottom of the interface, there are three options for you.
One is about a lock – "Click the lock to prevent further changes". You can click to lock it to make sure no one can edit the Time Machine preferences, because it needs password to open after you set it locked.
The second is "Show Time Machine Status". If you have checked it, the status of the Time Machine will be shown in the menu bar on the top of your Mac.
The last one is the question mark on the right bottom. If you still have any question, please check the help manual here.