The Essential Skills framework, as defined by the government of Canada, lists 9 Essential Skills for success in work, learning and life in Canada:
Here are some excellent sites with good information information about Essential Skills:
Employment and Skills Development Canada has created these online indicators for Reading, Document User and Numeracy so you can test your own Essential Skills.
Barron's Study Guides and Strategies is one of the best websites for learning that I have found, with lots of great information on learning, test-taking, conflict resolution, netiquette, etc.
Once you are confident in your language abilities, there are many opportunities for online learning. These are some websites that offer free, open courses. You just need to register and then you can enroll in courses.
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edX offers online courses for free. Two Canadian universities, the University of British Columbia and the University of Toronto, offer courses on edX.
EdX has courses on networking, interviews, grammar, IELTS test preparation, and writing essays.
The Khan Academy has many online courses that you can enroll in for free. Their website says, "You only have to know one thing: you can learn anything".
The Khan Academy has several courses on English grammar, as well as some test preparation courses.
The Canvas Network offers MOOCs (Massive Open Online Courses) on many different topics. Like the Khan Academy, all courses on Canvas are free.
Canvas has a couple of courses that may be of interest to you: Communication in Virtual and Mobile Work, and College Readiness: Reading, Writing, and Math. Most of their courses are on specialized topics.
Coursera offers university courses on many different topics.
They have several courses on English, including writing, speaking, grammar, and pronunciation, as well as business English for non-native speakers. .
FutureLearn also offers many courses on different topics.
This British site has courses on basic English, English for academic study, and English for the workplace.
GCF Learn Free has excellent materials for self-paced learning. Their information is more like tutorials than courses because you can do them anytime without signing up.
They have excellent materials for learning to use computers and computer programs.