Minimal SDL Runnable program, with Comments

CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
project(MyFirstSDL)

set(CMAKE_CXX_STANDARD 14)

add_executable(MyFirstSDL main.cpp)
target_link_libraries(MyFirstSDL SDL2)

main.cpp

#include <SDL2/SDL.h>

#define NAME "Window"
#define SCREEN_WIDTH 400
#define SCREEN_HEIGHT 400

int main() {
    SDL_Window *window = SDL_CreateWindow(
            NAME,
            SDL_WINDOWPOS_UNDEFINED,
            SDL_WINDOWPOS_UNDEFINED,
            SCREEN_WIDTH, SCREEN_HEIGHT,
            SDL_WINDOW_OPENGL); // No need to touch; This Initializes and creates your Window


    SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    // No need to touch; This gives you a Renderer, which you will pass to render functions so they know how and where to draw, in terms of the program Window

    for (;;) {
        // Let's Draw a simple pixel
        SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); // Here I define an RGBA color to draw with, this is set in the renderer, so the following function calls will use it, instead of you having to define a color each time;
        SDL_RenderDrawPoint(renderer, 40, 50); // Draws a single Pixel at coordinates [40, 50], based on the previously set color;
            // Remember, all coordinates are measured, from the TOP-Left corner;

        // Let's Draw a Rectangle, using an object
        SDL_Rect rect; // This is an object, which you can easily pass to a function to draw an entire rectangle
        rect.x = 100; // Top left corner X coordinate
        rect.y = 100; // Top left corner Y coordinate
        rect.w = 20; // Width
        rect.h = 20; // Height
        SDL_RenderFillRect(renderer, &rect); // Now we pass the rect and get it drawn to the screen

        SDL_RenderPresent(renderer); // Up until now, nothing happened, because all functions render to a buffer;
                                    // This tells SDL to write whatever is in the buffer to the screen;
    }

    return 0;
}