Tenses

Since I began to pracrice writing in English I figureed out that my knowledge of English was very poor despite studying in school about six years.
I can’t remember most of what I learned.

At the beginning, I forgot to attach articles to nouns all of my writing.
(I learned later that there were articles first,then nouns that follows them.But the way of thinking “attach articles to nouns” can't be easily changed.)
Articles is still hard for me to use correctly even after I was explainded and read some English grammer books.
Propositions is difficult, too. And tenses!

When I studied about present perfect (現在完了) for the first time in school, I couldn’t understand it.
I could understand present, past, future tenses.But present perfect? Past perfect?
I wondered why there're such tenses.

A friend of mine who l took a private lesson of English conversation from a native speaker once said,
“My teacher often use present perfect continuous.”
“Present,perfect,continuous? What is that ? Have we ever studied that?”
“I don’t remember.”

I think Japanese isn't strict about tenses compared to English.
Therefore, there is sometimes no difference between past tenses and present perfects tenses (or present perfect continuous) after translating English into Japanese.
But when it comes to write in English, its vagueness is my headache.