Create putpixel with SLD

I want graphic a point in c++ with SDL, I want to draw a pixel, what is my error? the window does not draw anything because?

I only want to use SDL for the creation of the window and the drawing of the putpixel, the line, the circumference and I will create it with the bresemham algorithm

I need the Point class to have its own class

#include "SDL.h"
#include <iostream>
#include "Point.h"
using namespace std;

int main(int argc, char* argv[])
{
    if (SDL_Init(SDL_INIT_VIDEO) == 0) {
        SDL_Window* window = NULL;
        Point point (100,100);//100 100 default values

        SDL_Renderer* renderer = point.getRender();

        if (SDL_CreateWindowAndRenderer(640, 480, 0, &window, &renderer) == 0) {
            SDL_bool done = SDL_FALSE;
            SDL_CreateRenderer(window,0,1);
            while (!done) {
                SDL_Event event;

                SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);
                SDL_RenderClear(renderer);

                SDL_SetRenderDrawColor(renderer, 255, 255, 255, SDL_ALPHA_OPAQUE);
                SDL_RenderDrawLine(renderer, 320, 200, 300, 240);
                point.putPixel(20,30);

                SDL_RenderPresent(renderer);

                while (SDL_PollEvent(&event)) {
                    if (event.type == SDL_QUIT) {
                        done = SDL_TRUE;
                    }
                }
            }
        }

        if (renderer) {
            SDL_DestroyRenderer(renderer);
        }
        if (window) {
            SDL_DestroyWindow(window);
        }
    }
    SDL_Quit();
    return 0;
}

and file .cpp

   #include "Point.h"
#include "SDL.h"

Point::Point(int x, int y): point(x) {
}

SDL_Renderer* renderer = NULL;

void Point::putPixel(int x,int y){
    SDL_SetRenderDrawColor(renderer, 100, 100, 100, SDL_ALPHA_OPAQUE);
    SDL_RenderDrawPoint(renderer, x, y);
}

SDL_Renderer* Point::getRender(){
return renderer;
}

and file .h

#include "SDL.h"
class Point
{
 private:
 int point;
 public:
 Point(int x,int y);
 void putPixel(int x, int y);
 SDL_Renderer* getRender();
};

the window shows blank.