The code looks like this:

#include"global.h"
static const int width = 800;
static const int height = 600;
int main (int argc, char **argv)
{
    SDL_Init(SDL_INIT_VIDEO);

    // Create the window
    SDL_Window *window = SDL_CreateWindow("Ferengine",SDL_WINDOWPOS_UNDEFINED,SDL_WINDOWPOS_UNDEFINED,width,height, SDL_WINDOW_OPENGL);
    // renderer
    SDL_Renderer *renderer = SDL_CreateRenderer(window,-1,SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
    // settings
    SDL_SetRenderDrawColor(renderer,255,0,0,255);
    SDL_SetWindowOpacity(window,1.0f);
    // loop 
    bool running = true;
    SDL_Event event;
    while(running) 
    {
        while(SDL_PollEvent(&event))
        {
            if(event.type == SDL_QUIT)
            {
                running = false;
            }
        }
    }
    SDL_RenderClear(renderer);

    SDL_RenderPresent(renderer);
    // release resources
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

global.h looks like this:

// SDL
#include <stdbool.h>
#include <SDL2/SDL.h>
#include <stdio.h>
#include <stdlib.h>

my make file looks like this

CC=gcc
S_DIR=Source
B_DIR=Build
build:
    $(CC) \
        -o \
        $(B_DIR)/Ferengine \
        $(S_DIR)/main.c \
        -lSDL2
clean:
    rm -f $(B_DIR)/*

file structure:

when I run make and then run the executable either the window is rendering whats behind it or it is transparent I saw another question like this but its answer did not work. I am using sdl2 version 2.0.22-2.