Hi Nam. I wish you well on your project.
Because this is a title I would capitalize the major words and make slight changes:
"The Difficulty of Studying English for Vietnamese Students and How to Improve"
Also your question:
May you help me to correct grammar become better?
Because you are asking another person, we say:
Will you help me.....
The complete question: Will you help me to correct my grammar and become better?
If you ask about yourself, we say:
May I.....
For example: May I borrow your pencil?