Ok, that is a very broad question. The concepts behind curly/curved arrow mechanisms take at least a chapter of a book to explain properly - I don't think the issue you have can be satisfactorily addressed on an Internet forum.
I suggest you look at some organic chemistry textbooks and come back with more specific questions.
I would recommend Reaction "Mechanisms At a Glance: A Stepwise Approach to Problem-Solving in Organic Chemistry - Mark Moloney", but any general organic text will probably be fine to get you started.