Terminology: Start here. Get to know the terminology of grammar. I did not grow up loving "grammar terminology" but I learned that knowing a little bit really helps.
Fairly Tale: Read it to understand differently. Without big grammar explanations, you will know and remember how it works -- giving you the pieces to put the grammar puzzle together.
The Q & A will also help with the mental picture, and so will the Language Comparisons help as an interesting resource.
The opening page is a graphical representation of all the lessons (beginner and advanced). Each link goes through to the lessons.
Your task: A. Understand and be able to figure it out.
B. Do so with fluidity. Building the ability to become automatic is the biggest challenge, not understanding as you may think. It is like watching someone else riding a unicycle and assuming mastery is easy. It ain't done till you sing! Once you can produce without hesitation, you can start to smile!
If you rush into the intermediate section without that fluid production ability of the beginner section, you are overloading the camel's back.
But, let me contradict myself as well. If you are not on an initial mastery conquest, but just snooping a bit to get a little familiar with the topics, it should be fine to study these topics. In fact, if you are really new to studying languages, it might be overwhelming and confusing. If you are familiar with foreign languages, this should be interesting and helpful. It is your call.