I think this depends significantly on your learning style, and how targeted you want your new learning to be.
For instance, I love classroom learning where it is possible to engage with the instructor and ask questions to make sure I have a thorough grasp of the topic or details. Classroom or lecture learning, including online, is great for a topic unfamiliar to me, where I don't know the questions to ask. Most of the time I prefer this to book learning.
However, I have a significant educational background in close reading of both literature from throughout history and ancient non-fiction writings. In the course of beginning my own creative writing (my first foray was long after finishing all of my schooling), I did a lot of basic how-to research both online and in the library. Therefore I already have a significant level of basic knowledge, though it may be incomplete, plus an assortment of more advanced techniques.
While there is much for me to learn, I think I would find it frustrating to take an online lecture course where I would have no control over the pacing and content, nor the ability to ask questions, in order to find those gems of new information that could help me with my actual project that I'm doing right now. If even the course syllabus is behind a paywall, how would I select one that matches my needs? And if I get through 10 hours of lectures and didn't solve my problems, would I then invest more time and money into a different series? Or five different ones?
You may want to ask yourself similar questions to figure out if a MOOC on creative writing is the right approach for learning the basics you need:
- Do you prefer audio and visual learning over reading and research?
- What, in your estimation, is your level of competence with English composition and grammar? Do you need to start with a composition course before taking a creative writing course?
- How much do you desire feedback as you learn? Perhaps you want a course with homework and critiques, such as you might get in a college course with peers and a professor, rather than a published online course.
- How widely read are you in the genre of your work? Can you recognize tropes and structural problems at a glance in someone else's book?
- You've already finished your first draft. Is what you really need a beta reader who can tell you generally what needs to be improved? (This can point you in the right direction to read up on basics.)
- Would you prefer to find skimmable resources where you can skip ahead over topics you know or don't care about in order to find the new bits?
If you think a course is the right approach for you, consider whether you would prefer a workshop, a course in a physical classroom, or a MOOC. Selecting which course(s) to take really depends on the needs you've identified.
Consider the following alternative resources
Like MOOCs, they're audio-based instruction and discussion. Unlike MOOCs, they're usually free, have searchable content and descriptions of each episode, and can cover all kinds of niche topics at their discretion. You can skip around.
I've recently found and fallen for Writing Excuses, which is an excellent podcast of brief (15-20 minute) episodes with panel discussion between established fiction writers from multiple genres, including a graphic novelist. They sometimes bring in star guests to cover topics in which they are expert. There are 14 year-long seasons, and you can even use the search bar to comb through episode transcripts. Season 13 (not in the sidebar menu for some reason, but you can search for it) is all about developing characters.
Here is a list of 20 recommended podcasts on writing.
Many sites publish articles to help you develop your writing, get published, and more. These are functionally similar to the podcasts, but in text format. In addition to the free content, these often offer critiques, editing services, and online courses as a business. Here are some I've found useful:
Writer's Digest has an enormous collection of resources and contributing authors. Check out the helpfully organized menu options for Articles, which let you browse by genre, your writing goals, the level of completion of your own work, and more.
Ian Irvine, bestselling fantasy novelist, stuffs his website with articles on the craft of writing.
Advanced Fiction Writing has tons of information all written by one enthusiastic professor.
The Writing Cooperative, which has helpful articles like How to Improve Your Grammar as a Writer, goes a step further in offering a Slack community for critiques and writing challenges.
Writer's Edit has some great articles on crafting and troubleshooting creative writing, as well as a pleasant format, though not much has been added recently.
Creative Writing Now, similar to the others, with sections geared toward teachers.
I've read many (but still a small fraction) of those on writing. Here are a few that stood out to me:
Making Shapely Fiction, by Jerome Stern. This guide emphasizes story structure. The second, larger part is an extended glossary of useful information (like a wiki for writing before wikipedia was a thing).
How Not to Write a Novel: 200 Classic Mistakes and How to Avoid Them—A Misstep-by-Misstep Guide, by Howard Mittelmark and Sandra Newman. A highly enjoyable parody of writing guides and a lampoon of poor writing, and you can learn a lot of basic tips from it on all aspects of writing.
On Writing: A Memoir of the Craft, by Stephen King. I'll let the blurb speak for itself:
"Long live the King" hailed Entertainment Weekly upon the publication of Stephen King's On Writing. Part memoir, part master class by one of the bestselling authors of all time, this superb volume is a revealing and practical view of the writer's craft, comprising the basic tools of the trade every writer must have. King's advice is grounded in his vivid memories from childhood through his emergence as a writer, from his struggling early career to his widely reported near-fatal accident in 1999 -- and how the inextricable link between writing and living spurred his recovery. Brilliantly structured, friendly and inspiring, On Writing will empower and entertain everyone who reads it -- fans, writers, and anyone who loves a great story well told.
You can also search for lists of books on writing for further ideas.