By using SSDL, you’ve gone most of the way toward becoming an SDL programmer. To keep going, you can
Dump SSDL and get a tutorial on SDL. You’ll see a lot that you recognize. Many SSDL functions are SDL functions with an “S” stuck on the front (as in, SDL_PollEvent became SSDL_PollEvent). Usually SDL functions need one more initial argument, often of type SDL_Window* or SDL_Renderer*, two types you’ll learn right away. You can usually guess what’ll be needed (hint: functions with “Render” in the name probably need SDL_Renderer*).
Or, keep SSDL, but extend with more SDL features – say, joystick ...
