re: I dont no how shoud i implement this snippet
You would install the Code Snippets plugin and add it as a new code snippet. Be sure to save and activate the snippet.
re: I need an exact search over Categories like in post (not AND/OR only explezit AND
This snippets not going to do that. It will only return entries as results have the exact phrase entered by the user. There is no OR/AND operation, only exact. Additionally, it does not search categories. That is what the category drop down filter is for on cMap.
Not sure if my answers helps, but hope it does.