The most direct and simple explanation is that an online course is a course conducted over the Internet. In order to participate in your class you will be required to log in over the internet and do things like access class documents, read announcements, communicate with your instructor and classmates, complete assignments, participate in discussions and groupwork, and take quizzes and tests.
Most of your work in an online class will be asynchronous, which means you can do your coursework at whatever time of the day you want even at 2a.m. in your pajamas. Just be sure, of course, to submit your work by the required deadlines.
The exception to participating at your own timeframe is during weekly required chats. Sure, you can still wear your pajamas, but these chats take place once a week in a chatroom or in a webconference, and they are conducted in real-time, synchronously. Your instructor will announce the dates and times when your course begins so you can plan your schedule through the next 8 weeks of class.
Casa Loma’s courses are designed in a linear format using weekly modules. In other words, you complete one module per week before moving to the next, and you work within the instructor's timeline, not yours. Coursed are not self-paced.
In a sense there is flexibility within each module, however, in that you can complete your assignments and submit them any time within the week. You can also post to the discussion forums anytime within the week so long as you are sure to post at least three different days.