Watch videos that describe the skill. A visual demonstration can help you learn a skill faster than if you had to read a set of instructions. YouTube is one free source for how-to videos on just about anything.
Join an online exchange group. Learn a foreign language by becoming an active member of an Internet-based language exchange site such as ITalki or My Language Exchange. Such sites allow you to host classes in your native language to earn credits to get free classes from others. My Language Exchange pairs you up with students whose language you want to learn and who want to learn your native language.
Read skill instructions and background information on sites devoted to the skill or on websites of the skill's associations and clubs. Look for "how-to" or "background" or "about" sections of the website to find the information you are looking for.
Find university-level free courses online available from universities all over the world. Various subjects are offered online for free, and they often take the form of video courses or text. Some universities offering free courses include the Massachusetts Institute of Technology, the University of Southern Queensland (Australia) and the University of California, Berkeley.