Question

How to register for a course ?

Answer 1

Go to the website and just start at the first page
http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00sc-introduction-to-computer-science-and-programming-spring-2011/index.htm

You don't have to sign up or in or anything - just start watching the videos try the homework problems - see the solutions and learn :)

Answer 2

There is also an edX version of this MIT course (6.00x) that will run from October 1, 2012 - Jan 14, 2013. It will cover the same material included in the OCW 6.00 version but will include graded homework and exams. You can register for the edX course here https://www.edx.org/courses/MITx/6.00x/2012_Fall/about