Final thoughts about grammar
The important grammar topics, such as verb tenses, the articles and the passive, are briefly covered in the explanation and quiz pages on this website.
The English language, however, contains much more 'grammar' than contained here. The ambitious learner, therefore, should invest in a good reference work such as Swan's Practical English Usage.
Ambitious learners can also do individual 'research' via the internet. You will find many suggestions in language learning online.
A third good way to get grammar and usage advice is to ask a question on a language forum such as the two Stack Exchange English language sites. I have answered many questions about grammar and vocabulary on these sites. You can also ask me a question directly via the Contact link below.
A final thought: Grammar is not the most important thing about learning a language - as this cartoon will show you!
Good luck to all learners of English who have visited my website!