.Don't get too hung up on perfect grammar, but don't think it doesn't matter either

The main point of learning a language is to be able to communicate, and using the wrong grammar can lead to misunderstandings, so you do need to get the words in the right order.  That said, learning about a language is different to learning a language

As a child we learn to communicate without the benefit of grammar books

Of course you're an adult, and as such you can use grammar books to read about English grammar and to test your grammar, but once you think you've learnt something you have to practice it again and again, and in a more realistic situation than on a blank sheet of paper

.Learn the different tenses. Learn by heart a simple example sentence using each tense

.Do online exercises

.Keep a note of how you did and go back in a few weeks to see how you have improved