You've been asked this in an interview for a DBA position I would assume?  If that assumption is not true, please ignore the rest of this message.  If it's true:

1.  You need to go spend some money on SQL Server books and begin reading.  Don't stop until you have read at least 20 of them and taken notes.

2.  You need to read Books Online.  Everything in Books Online.  Take notes.

3.  Perform some backups.  Try to restore from them.  Do this based on what you have read in steps 1 and 2.

4.  If you can't get 3 to work, find another line of work.

5.  Go back to line 1, replacing 3 with something else you've hopefully learned in 1 and 2.