By Leah Yamshon, Macworld.com | Mar 20, 2012
If you’re restoring your entire system from a backup—in the event of a crash or if you wanted to start over from a specific backup—connect your Time Machine drive, and start up your Mac from the Lion recovery partition by holding Command-R at startup. (Or, if you have one, you can use your Mac OS X installation disk.)
A window called Mac OS X Utilities will appear. Select Restore from Time Machine Backup.
Select your Time Machine drive, then the backup you want to restore from, and then select your destination drive—the hard drive on your Mac.
Let’s say you bought a new Mac and want to restore data from your old system, or you want to transfer data from one Mac to another. Use a utility called Migration Assistant. Once your backup drive is connected, go to Finder -> Applications -> Utilities, then open Migration Assistant. An intro to Migration Assistant will ask how you want to transfer your information, so click “From another Mac, PC, Time Machine backup, or other disk,” and then Continue.
Next, you’ll be asked to select your Migration Method—click “From a Time Machine backup or other disk.”
Select your backup drive, then choose which items you’d like to Migrate. Click Continue, and your files will begin to transfer.