guys I downloaded this template and I would like to make particles shoot gun as well as the video, as I do to make this effect shot (particles, etc.)
So are you asking how to make particles?
FIRST! Go to youtube lol 
Onward from there https://youtube.com/watch?v=OXK2Xbd7D9w
Should give you the basics. Besides that you’ll need the things you’ll plug into the particle, if your familiar with the term texture, static mesh, etc, youll need those as well.