Just head to www.edx.org and register (it's all free). Within the next 2 or 3 months, EdX will launch a course called "Introduction to Linux". This full course, developed by the Linux Foundation, was previously offered on a commercial basis at $2400, so it's bound to be good. If you want to sign up now, ready to take it when it's ready, just visit www.edx.org. You can also explore all of the other courses that are ready to study.
Source: http://www.techsupportalert.com/content/coming-soon-take-2400-linux-course-free.htm
Source: http://www.techsupportalert.com/content/coming-soon-take-2400-linux-course-free.htm