Hi Lau,

The first thing to master is the sentence structure. Subject, verb, object (direct/indirect), and any descriptions of each component using adverbs, adjectives, and so on.

It's a building block of studying each sentence component and eventually becoming proficient in the sentence construction.

It takes time, dedication, and determination over several years.

That said, please do not be put off. 

Mastering a second language is very rewarding but is a hard slog with satisfaction coming slowly but surely.

Bonne continuation. 

Jim