1 Don’t expect you can learn correct grammatical English by learning the tenses by heart.
It’s better to learn a language by practising “real language:” by reading stories or articles and talking to someone else. In the past students did have to do endless exercises with tenses, and in many schools all over the world this is still the practise today. But the results of this are not very good.
2 If you try to learn all the tenses together you won’t remember anything.
You need to learn the tenses one by one, and slowly. You will learn the tenses if you keep reading this blog and do the exercises. Practise the same tense until you know it well. Don’t learn them all together. It just doesn’t work.
3 Learning English is not the same as learning a set of rules.
Unfortunately, learning tenses is not like learning math. If you learn a rule in math, you will be able to solve all the problems that use this rule. In languages, it works the other way: the examples will teach you the rule. Some tenses in English aren’t easy at all to understand, and it can happen that you need to see or hear hundreds of examples before you will really understand how it works. That is a normal part of learning a language, and it doesn’t mean you’re slow!