Mixing Blueprint and C++

Guys, Im a complete begginer at this, as such have understood very little. I was following the youtube videos and making something using what I learnt, and have come upon the videos based on programming. So, as I am solo and don’t have any team, am just working on learning UE4. So, my quetions isn’t should I use C++ or not, nor when to use C++ or stuff like that.
It is pretty simple, I have a game made from a BP template and want to use C++ as if I had started from a C++ template. Do I have to start over or is it possible to add code to my existing project?
Also, if I start using a C++ template, how do I use Blueprints?
A good example would be in the first answer, all I want to know is “How to add the component, and where exactly do I make it(somewhere else, visual studio, new project etc.)”.