Grammar can be difficult even when in you own native language, right? When you start to learn a foreign language, then grammar really, really, really sucks! Although it sucks, you are often trying to understand why certain rules are what they are. I am a language teacher and often students ask me “why do you use this preposition, instead of this other one?” or, “Why do I need to use this article?”, “why this word has so many different meanings”, “how can I know which option to use?”. The answer is simple: You don’t need to know when you first start learning.
Think about how children learn a language. They hear it, they repeat it, without understanding the roles of them. They just realized what works, what does not work and that is how they start speaking. Grammar is important? YES! It is, but you don’t need to worry about it when you first start.