Dear Afreen,
Welcome to JavaRanch. Please have a look at
SCJPFAQ
On other hand, do the following needful, if you are new to java.
Pickup Head First Java and completely go through itWrite plenty of code to understand the conceptsPickup Sun Certified Java Programmer Guide from K&B and carefully go through it and solve self test questionsPickup exam simulators like Enthuware and ExamLab and practice mock questions
It will help you to get on track.
HTH,
Ben