NET stands for National Eligibility Test which is conducted by UGC.This exam will be happen twice time in a year.
Those candidate have completed masters degree from recognized university are eligible for NET exam.
For general and OBC candidate must be hold 55%above in masters degree. SC/ST candidate must be hold 50% above in masters degree.
For Junior research fellowship course your age must be in between 19 to 28 years.
For lectureship ,There is no upper age limit but the Minimum age is 19 years.
I have attached some Question paper of English for NET exam .Please check it out.This paper are really helpful for you.
For more details about UGC exam you can visit to http://www.ugc.ac.in/