A lot of us use computers on a daily basis. For those who are interested in knowing more about Operating Systems (OS), Linus is the most important OS to learn and work with.
If you are interested in knowing more about Linus, you can follow the online course Introduction to Linux offered by the Linux Foundation. on the MOOC platform edX (which is basically a website that hosts online university-level courses in a wide range of disciplines).
After you register for a free account on edX (You can also login using your Facebook account), you will be able to pursue the course which is offered in English (English transcripts are also available!)
Link: Introduction to Linux
PS. : There are many more courses in different fields of science that can help you prepare for your universities studies (if you are planning to apply to a university), or just to learn new things!!