I have had a look back through this discussion and I thought it was important to help you with some fundamentals.
At the start if the post you were looking for instruction in 'systematic' form. This is in indeed available if you click on Support and Learning > Start here at the top of this page. This will take you to the URL https://www.autodesk.com/products/fusion-360/get-started.
If you click on Start Learning on that page you will get to the structured Fusion 360 adoption portal. http://f360ap.autodesk.com/courses
This is a really good place to start. I assume you will need to start at Foundational Concepts, though perhaps counterintuitively it is at the bottom of the list.
What is perhaps better is to click on Learn more which is in my opinion better presented in terms of the 'standard text book nature' you refer to.
The beauty of the pages in the adoption portal is that they allow you to monitor your progress through the courses.
Watching YouTube videos is useful but it is better done after or in support of these reference pages. Whilst I don't mean to disrespect the work of some very good originators of YouTube content you have to be careful that the collective mindset doesn't lead you to follow unhelpful workflows. One such example is the use of joints to position components. Don't get me wrong this is a useful technique but I wonder if some people are using it to the point that their models have conflicting joints and confusion. It is in my opinion; and that is the opinion of a rank amateur, far better to align components when you want to align components and use use joints as... well joints.
Looking at what you want to do, I think (I can't be sure) that you were trying to create geometry on a plane tangent to the surface of your quadball. For this you do not require joints (or alignment for that matter). It would be far more efficient to simply use a plane at angle on a construction line tangent to the projection of the outer surface to your quadball.
I hope this is helpful and I apologise to you and Jeff for inserting my opinions into this discussion, it just seemed right to do so.