when to use to-V and V-ing?
my head is about explode because of very many case of using it.
I learned it on the internet and found a big bunch of how to use it.
example: - use to-V when follow these verbs: forget, help, learn, teach, train, choose, expect, hope, need, offer, want, would like, agree, encourage, pretend, promise, allow, can/can't afford, decide, manage, mean, refuse.
- use V-ing when follow these verbs: void, dislike, enjoy, finish, give up, mind/not mind, practise.
how can I remember all of it easily?

Question

when to use to-V and V-ing?
my head is about explode because of very many case of using it. 
I learned it on the internet and found a big bunch of how to use it. 
example: - use to-V when follow these verbs: forget, help, learn, teach, train, choose, expect, hope, need, offer, want, would like, agree, encourage, pretend, promise, allow, can/can't afford, decide, manage, mean, refuse.
- use V-ing when follow these verbs: void, dislike, enjoy, finish, give up, mind/not mind, practise.
how can I remember all of it easily?

Answer

The answer, sadly, is to practice, practice, practice. Here is a great page with loads of exercises: http://www.englishpage.com/gerunds/index.htm

From your question, I don't think you have fully understood the grammar here. It is NOT true that these words are ALWAYS V-ING or TO-V, it depends on the type of sentences that they are in and the role that they play.

I hope that the link I shared will help you to learn more!

As a general tip: if you are unsure, always choose V-ING, it is much more common in every day use that TO-V (although you will learn there are many cases that you must use "to").

Good luck, Tom