Japanese problem, I'm just an amateur, don't laugh at me!

The average Japanese can only write simple Chinese characters. The basic words you just started to learn should be written in Chinese characters (green, empty, simple, reluctant, etc.). This is more standardized and helps you remember the pronunciation and training of each Chinese character.

Lowercase kana is pronunciation.

He's pronunciation ... is similar to English phonetic symbols. Can you say the word helicopter? It's similar to that sound, and then it's a little quieter.

Yo is yo, and yu is equivalent to you in English.

Grammar is still to be learned. For example, verbs and adjectives are deformed, hypothetical and possible, passive and causative. If you don't learn them, you won't know what those verbs mean even if you read this article.

These are the most basic, of course, it doesn't matter if you don't learn specific exam grammar.

I recommend you to use the standard Japanese for communication between China and Japan published by People's Education Press. Self-study from 0 is also applicable, with detailed explanations and sufficient examples.