I am an electrical engineer and I want to appear for GRE. I am interested in software field but not able to decide where to start preparing. I also need suggestions about the fields I can apply for in my own discipline?

From your background I am assuming that you have recently graduated or about to. Also it appears that you do not have prior programming experience. What you need to do is read through these: Start with one programming language and practice every day. You will also need an ability to break things down to first principles and attempt bring those concepts 'to life' via code. Read some popular text books but don't just stop there - code and get your hands dirty. Code every day. As for disciplines in your own field, I was expecting you to have zeroed in on some majors by now but I can say that I know a lot of electrical engineers who focussed on transmission and distribution systems and power electronics shift focus to VLSI in graduate school and land jobs in companies like Intel and AMD.