Without any foundation, how to understand China's classic ancient books step by step?

You can find some classical prose first. Read more articles about scenery. Will attract you in. Such as: Peach Blossom Garden. . Xiaoshitang . From shallow to deep. Read some essays. Such as: Ishigaki official. etc

Classical Chinese grammar is more complicated, if we simply start with the basic skills of classical Chinese like students. It will make you lose interest.

Read the article as a whole first. Understand the part of the article that attracts you. If you don't understand, read the notes again.

Although the ancient prose is rather crude, after understanding it. There will be a different kind of elegance in it