Hello Reddy, Greetings!

Well, Coursera is an online portal which contains various courses mainly of computer science related . Here one can enroll for the different courses and complete them under the given time. In the course there will be professionals who will teach you about the course, there will be assignments .

They also provide certification for the courses, but it us paid . But they also provide financial aid to the needy so one can try for it also. Overall it is a good place for e-learning .

Thank you, hope this helps.